diff --git a/src/api/mod.rs b/src/api/mod.rs
index b698a85..f64db62 100644
--- a/src/api/mod.rs
+++ b/src/api/mod.rs
@@ -174,6 +174,31 @@ pub trait BacklogApi {
     fn get_project_versions(&self, _key: &str) -> Result<Vec<ProjectVersion>> {
         unimplemented!()
     }
+    fn add_project_version(
+        &self,
+        _key: &str,
+        _name: &str,
+        _description: Option<&str>,
+        _start_date: Option<&str>,
+        _release_due_date: Option<&str>,
+    ) -> Result<ProjectVersion> {
+        unimplemented!()
+    }
+    fn update_project_version(
+        &self,
+        _key: &str,
+        _version_id: u64,
+        _name: &str,
+        _description: Option<&str>,
+        _start_date: Option<&str>,
+        _release_due_date: Option<&str>,
+        _archived: Option<bool>,
+    ) -> Result<ProjectVersion> {
+        unimplemented!()
+    }
+    fn delete_project_version(&self, _key: &str, _version_id: u64) -> Result<ProjectVersion> {
+        unimplemented!()
+    }
     fn create_project(&self, _params: &[(String, String)]) -> Result<Project> {
         unimplemented!()
     }
@@ -548,6 +573,42 @@ impl BacklogApi for BacklogClient {
         self.get_project_versions(key)
     }
 
+    fn add_project_version(
+        &self,
+        key: &str,
+        name: &str,
+        description: Option<&str>,
+        start_date: Option<&str>,
+        release_due_date: Option<&str>,
+    ) -> Result<ProjectVersion> {
+        self.add_project_version(key, name, description, start_date, release_due_date)
+    }
+
+    fn update_project_version(
+        &self,
+        key: &str,
+        version_id: u64,
+        name: &str,
+        description: Option<&str>,
+        start_date: Option<&str>,
+        release_due_date: Option<&str>,
+        archived: Option<bool>,
+    ) -> Result<ProjectVersion> {
+        self.update_project_version(
+            key,
+            version_id,
+            name,
+            description,
+            start_date,
+            release_due_date,
+            archived,
+        )
+    }
+
+    fn delete_project_version(&self, key: &str, version_id: u64) -> Result<ProjectVersion> {
+        self.delete_project_version(key, version_id)
+    }
+
     fn create_project(&self, params: &[(String, String)]) -> Result<Project> {
         self.create_project(params)
     }
diff --git a/src/api/project.rs b/src/api/project.rs
index b0666e1..b022cce 100644
--- a/src/api/project.rs
+++ b/src/api/project.rs
@@ -290,6 +290,81 @@ impl BacklogClient {
         })
     }
 
+    pub fn add_project_version(
+        &self,
+        key: &str,
+        name: &str,
+        description: Option<&str>,
+        start_date: Option<&str>,
+        release_due_date: Option<&str>,
+    ) -> Result<ProjectVersion> {
+        let mut params = vec![("name".to_string(), name.to_string())];
+        if let Some(d) = description {
+            params.push(("description".to_string(), d.to_string()));
+        }
+        if let Some(s) = start_date {
+            params.push(("startDate".to_string(), s.to_string()));
+        }
+        if let Some(r) = release_due_date {
+            params.push(("releaseDueDate".to_string(), r.to_string()));
+        }
+        let value = self.post_form(&format!("/projects/{}/versions", key), &params)?;
+        serde_json::from_value(value.clone()).map_err(|e| {
+            anyhow::anyhow!(
+                "Failed to deserialize add project version response: {}\nRaw JSON:\n{}",
+                e,
+                serde_json::to_string_pretty(&value).unwrap_or_else(|_| value.to_string())
+            )
+        })
+    }
+
+    pub fn update_project_version(
+        &self,
+        key: &str,
+        version_id: u64,
+        name: &str,
+        description: Option<&str>,
+        start_date: Option<&str>,
+        release_due_date: Option<&str>,
+        archived: Option<bool>,
+    ) -> Result<ProjectVersion> {
+        let mut params = vec![("name".to_string(), name.to_string())];
+        if let Some(d) = description {
+            params.push(("description".to_string(), d.to_string()));
+        }
+        if let Some(s) = start_date {
+            params.push(("startDate".to_string(), s.to_string()));
+        }
+        if let Some(r) = release_due_date {
+            params.push(("releaseDueDate".to_string(), r.to_string()));
+        }
+        if let Some(a) = archived {
+            params.push(("archived".to_string(), a.to_string()));
+        }
+        let value = self.patch_form(
+            &format!("/projects/{}/versions/{}", key, version_id),
+            &params,
+        )?;
+        serde_json::from_value(value.clone()).map_err(|e| {
+            anyhow::anyhow!(
+                "Failed to deserialize update project version response: {}\nRaw JSON:\n{}",
+                e,
+                serde_json::to_string_pretty(&value).unwrap_or_else(|_| value.to_string())
+            )
+        })
+    }
+
+    pub fn delete_project_version(&self, key: &str, version_id: u64) -> Result<ProjectVersion> {
+        let value = self.delete_req(&format!("/projects/{}/versions/{}", key, version_id))?;
+        serde_json::from_value(value.clone()).map_err(|e| {
+            anyhow::anyhow!(
+                "Failed to deserialize delete project version response: {}\nRaw JSON:\n{}",
+                e,
+                serde_json::to_string_pretty(&value).unwrap_or_else(|_| value.to_string())
+            )
+        })
+    }
+
     pub fn get_project_versions(&self, key: &str) -> Result<Vec<ProjectVersion>> {
         let value = self.get(&format!("/projects/{}/versions", key))?;
         serde_json::from_value(value.clone()).map_err(|e| {
diff --git a/src/cmd/project/version.rs b/src/cmd/project/version.rs
index b97b6d2..787c352 100644
--- a/src/cmd/project/version.rs
+++ b/src/cmd/project/version.rs
@@ -14,6 +14,86 @@ impl ProjectVersionListArgs {
     }
 }
 
+pub struct ProjectVersionAddArgs {
+    key: String,
+    name: String,
+    description: Option<String>,
+    start_date: Option<String>,
+    release_due_date: Option<String>,
+    json: bool,
+}
+
+impl ProjectVersionAddArgs {
+    pub fn new(
+        key: String,
+        name: String,
+        description: Option<String>,
+        start_date: Option<String>,
+        release_due_date: Option<String>,
+        json: bool,
+    ) -> Self {
+        Self {
+            key,
+            name,
+            description,
+            start_date,
+            release_due_date,
+            json,
+        }
+    }
+}
+
+pub struct ProjectVersionUpdateArgs {
+    key: String,
+    version_id: u64,
+    name: String,
+    description: Option<String>,
+    start_date: Option<String>,
+    release_due_date: Option<String>,
+    archived: Option<bool>,
+    json: bool,
+}
+
+impl ProjectVersionUpdateArgs {
+    pub fn new(
+        key: String,
+        version_id: u64,
+        name: String,
+        description: Option<String>,
+        start_date: Option<String>,
+        release_due_date: Option<String>,
+        archived: Option<bool>,
+        json: bool,
+    ) -> Self {
+        Self {
+            key,
+            version_id,
+            name,
+            description,
+            start_date,
+            release_due_date,
+            archived,
+            json,
+        }
+    }
+}
+
+pub struct ProjectVersionDeleteArgs {
+    key: String,
+    version_id: u64,
+    json: bool,
+}
+
+impl ProjectVersionDeleteArgs {
+    pub fn new(key: String, version_id: u64, json: bool) -> Self {
+        Self {
+            key,
+            version_id,
+            json,
+        }
+    }
+}
+
 pub fn list(args: &ProjectVersionListArgs) -> Result<()> {
     let client = BacklogClient::from_config()?;
     list_with(args, &client)
@@ -34,6 +114,74 @@ pub fn list_with(args: &ProjectVersionListArgs, api: &dyn BacklogApi) -> Result<
     Ok(())
 }
 
+pub fn add(args: &ProjectVersionAddArgs) -> Result<()> {
+    let client = BacklogClient::from_config()?;
+    add_with(args, &client)
+}
+
+pub fn add_with(args: &ProjectVersionAddArgs, api: &dyn BacklogApi) -> Result<()> {
+    let version = api.add_project_version(
+        &args.key,
+        &args.name,
+        args.description.as_deref(),
+        args.start_date.as_deref(),
+        args.release_due_date.as_deref(),
+    )?;
+    if args.json {
+        println!(
+            "{}",
+            serde_json::to_string_pretty(&version).context("Failed to serialize JSON")?
+        );
+    } else {
+        println!("Added: {}", format_version_row(&version));
+    }
+    Ok(())
+}
+
+pub fn update(args: &ProjectVersionUpdateArgs) -> Result<()> {
+    let client = BacklogClient::from_config()?;
+    update_with(args, &client)
+}
+
+pub fn update_with(args: &ProjectVersionUpdateArgs, api: &dyn BacklogApi) -> Result<()> {
+    let version = api.update_project_version(
+        &args.key,
+        args.version_id,
+        &args.name,
+        args.description.as_deref(),
+        args.start_date.as_deref(),
+        args.release_due_date.as_deref(),
+        args.archived,
+    )?;
+    if args.json {
+        println!(
+            "{}",
+            serde_json::to_string_pretty(&version).context("Failed to serialize JSON")?
+        );
+    } else {
+        println!("Updated: {}", format_version_row(&version));
+    }
+    Ok(())
+}
+
+pub fn delete(args: &ProjectVersionDeleteArgs) -> Result<()> {
+    let client = BacklogClient::from_config()?;
+    delete_with(args, &client)
+}
+
+pub fn delete_with(args: &ProjectVersionDeleteArgs, api: &dyn BacklogApi) -> Result<()> {
+    let version = api.delete_project_version(&args.key, args.version_id)?;
+    if args.json {
+        println!(
+            "{}",
+            serde_json::to_string_pretty(&version).context("Failed to serialize JSON")?
+        );
+    } else {
+        println!("Deleted: {}", format_version_row(&version));
+    }
+    Ok(())
+}
+
 fn format_version_row(v: &ProjectVersion) -> String {
     let dates = match (&v.start_date, &v.release_due_date) {
         (Some(s), Some(e)) => format!(" ({} → {})", s, e),
@@ -51,12 +199,49 @@ mod tests {
     use anyhow::anyhow;
 
     struct MockApi {
-        versions: Option<Vec<ProjectVersion>>,
+        list: Option<Vec<ProjectVersion>>,
+        single: Option<ProjectVersion>,
+    }
+
+    fn mock(list: Option<Vec<ProjectVersion>>, single: Option<ProjectVersion>) -> MockApi {
+        MockApi { list, single }
     }
 
     impl crate::api::BacklogApi for MockApi {
         fn get_project_versions(&self, _key: &str) -> anyhow::Result<Vec<ProjectVersion>> {
-            self.versions.clone().ok_or_else(|| anyhow!("no versions"))
+            self.list.clone().ok_or_else(|| anyhow!("list failed"))
+        }
+
+        fn add_project_version(
+            &self,
+            _key: &str,
+            _name: &str,
+            _description: Option<&str>,
+            _start_date: Option<&str>,
+            _release_due_date: Option<&str>,
+        ) -> anyhow::Result<ProjectVersion> {
+            self.single.clone().ok_or_else(|| anyhow!("add failed"))
+        }
+
+        fn update_project_version(
+            &self,
+            _key: &str,
+            _version_id: u64,
+            _name: &str,
+            _description: Option<&str>,
+            _start_date: Option<&str>,
+            _release_due_date: Option<&str>,
+            _archived: Option<bool>,
+        ) -> anyhow::Result<ProjectVersion> {
+            self.single.clone().ok_or_else(|| anyhow!("update failed"))
+        }
+
+        fn delete_project_version(
+            &self,
+            _key: &str,
+            _version_id: u64,
+        ) -> anyhow::Result<ProjectVersion> {
+            self.single.clone().ok_or_else(|| anyhow!("delete failed"))
         }
     }
 
@@ -107,9 +292,7 @@ mod tests {
 
     #[test]
     fn list_with_text_output_succeeds() {
-        let api = MockApi {
-            versions: Some(vec![sample_version()]),
-        };
+        let api = mock(Some(vec![sample_version()]), None);
         assert!(
             list_with(
                 &ProjectVersionListArgs::new("TEST".to_string(), false),
@@ -121,20 +304,132 @@ mod tests {
 
     #[test]
     fn list_with_json_output_succeeds() {
-        let api = MockApi {
-            versions: Some(vec![sample_version()]),
-        };
+        let api = mock(Some(vec![sample_version()]), None);
         assert!(list_with(&ProjectVersionListArgs::new("TEST".to_string(), true), &api).is_ok());
     }
 
     #[test]
     fn list_with_propagates_api_error() {
-        let api = MockApi { versions: None };
+        let api = mock(None, None);
         let err = list_with(
             &ProjectVersionListArgs::new("TEST".to_string(), false),
             &api,
         )
         .unwrap_err();
-        assert!(err.to_string().contains("no versions"));
+        assert!(err.to_string().contains("list failed"));
+    }
+
+    #[test]
+    fn add_with_text_output_succeeds() {
+        let api = mock(None, Some(sample_version()));
+        let args = ProjectVersionAddArgs::new(
+            "TEST".to_string(),
+            "v1.0".to_string(),
+            None,
+            None,
+            None,
+            false,
+        );
+        assert!(add_with(&args, &api).is_ok());
+    }
+
+    #[test]
+    fn add_with_json_output_succeeds() {
+        let api = mock(None, Some(sample_version()));
+        let args = ProjectVersionAddArgs::new(
+            "TEST".to_string(),
+            "v1.0".to_string(),
+            None,
+            None,
+            None,
+            true,
+        );
+        assert!(add_with(&args, &api).is_ok());
+    }
+
+    #[test]
+    fn add_with_propagates_api_error() {
+        let api = mock(None, None);
+        let args = ProjectVersionAddArgs::new(
+            "TEST".to_string(),
+            "v1.0".to_string(),
+            None,
+            None,
+            None,
+            false,
+        );
+        let err = add_with(&args, &api).unwrap_err();
+        assert!(err.to_string().contains("add failed"));
+    }
+
+    #[test]
+    fn update_with_text_output_succeeds() {
+        let api = mock(None, Some(sample_version()));
+        let args = ProjectVersionUpdateArgs::new(
+            "TEST".to_string(),
+            3,
+            "v1.1".to_string(),
+            None,
+            None,
+            None,
+            None,
+            false,
+        );
+        assert!(update_with(&args, &api).is_ok());
+    }
+
+    #[test]
+    fn update_with_json_output_succeeds() {
+        let api = mock(None, Some(sample_version()));
+        let args = ProjectVersionUpdateArgs::new(
+            "TEST".to_string(),
+            3,
+            "v1.1".to_string(),
+            None,
+            None,
+            None,
+            Some(true),
+            true,
+        );
+        assert!(update_with(&args, &api).is_ok());
+    }
+
+    #[test]
+    fn update_with_propagates_api_error() {
+        let api = mock(None, None);
+        let args = ProjectVersionUpdateArgs::new(
+            "TEST".to_string(),
+            3,
+            "v1.1".to_string(),
+            None,
+            None,
+            None,
+            None,
+            false,
+        );
+        let err = update_with(&args, &api).unwrap_err();
+        assert!(err.to_string().contains("update failed"));
+    }
+
+    #[test]
+    fn delete_with_text_output_succeeds() {
+        let api = mock(None, Some(sample_version()));
+        let args = ProjectVersionDeleteArgs::new("TEST".to_string(), 3, false);
+        assert!(delete_with(&args, &api).is_ok());
+    }
+
+    #[test]
+    fn delete_with_json_output_succeeds() {
+        let api = mock(None, Some(sample_version()));
+        let args = ProjectVersionDeleteArgs::new("TEST".to_string(), 3, true);
+        assert!(delete_with(&args, &api).is_ok());
+    }
+
+    #[test]
+    fn delete_with_propagates_api_error() {
+        let api = mock(None, None);
+        let args = ProjectVersionDeleteArgs::new("TEST".to_string(), 3, false);
+        let err = delete_with(&args, &api).unwrap_err();
+        assert!(err.to_string().contains("delete failed"));
     }
 }
diff --git a/src/main.rs b/src/main.rs
index ddd613d..187823f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -43,7 +43,10 @@ use cmd::project::status::{
     ProjectStatusUpdateArgs,
 };
 use cmd::project::user::{ProjectUserAddArgs, ProjectUserDeleteArgs, ProjectUserListArgs};
-use cmd::project::version::ProjectVersionListArgs;
+use cmd::project::version::{
+    ProjectVersionAddArgs, ProjectVersionDeleteArgs, ProjectVersionListArgs,
+    ProjectVersionUpdateArgs,
+};
 use cmd::project::{
     ProjectActivitiesArgs, ProjectCreateArgs, ProjectDeleteArgs, ProjectDiskUsageArgs,
     ProjectListArgs, ProjectShowArgs, ProjectUpdateArgs,
@@ -656,6 +659,63 @@ enum ProjectVersionCommands {
         #[arg(long)]
         json: bool,
     },
+    /// Add a version to a project
+    Add {
+        /// Project ID or key
+        id_or_key: String,
+        /// Version name
+        #[arg(long)]
+        name: String,
+        /// Description
+        #[arg(long)]
+        description: Option<String>,
+        /// Start date (YYYY-MM-DD)
+        #[arg(long)]
+        start_date: Option<String>,
+        /// Release due date (YYYY-MM-DD)
+        #[arg(long)]
+        release_due_date: Option<String>,
+        /// Output as JSON
+        #[arg(long)]
+        json: bool,
+    },
+    /// Update a version in a project
+    Update {
+        /// Project ID or key
+        id_or_key: String,
+        /// Version ID
+        #[arg(long)]
+        version_id: u64,
+        /// Version name
+        #[arg(long)]
+        name: String,
+        /// Description
+        #[arg(long)]
+        description: Option<String>,
+        /// Start date (YYYY-MM-DD)
+        #[arg(long)]
+        start_date: Option<String>,
+        /// Release due date (YYYY-MM-DD)
+        #[arg(long)]
+        release_due_date: Option<String>,
+        /// Mark as archived
+        #[arg(long)]
+        archived: Option<bool>,
+        /// Output as JSON
+        #[arg(long)]
+        json: bool,
+    },
+    /// Delete a version from a project
+    Delete {
+        /// Project ID or key
+        id_or_key: String,
+        /// Version ID
+        #[arg(long)]
+        version_id: u64,
+        /// Output as JSON
+        #[arg(long)]
+        json: bool,
+    },
 }
 
 #[derive(Subcommand)]
@@ -1742,6 +1802,47 @@ fn run() -> Result<()> {
                 ProjectVersionCommands::List { id_or_key, json } => {
                     cmd::project::version::list(&ProjectVersionListArgs::new(id_or_key, json))
                 }
+                ProjectVersionCommands::Add {
+                    id_or_key,
+                    name,
+                    description,
+                    start_date,
+                    release_due_date,
+                    json,
+                } => cmd::project::version::add(&ProjectVersionAddArgs::new(
+                    id_or_key,
+                    name,
+                    description,
+                    start_date,
+                    release_due_date,
+                    json,
+                )),
+                ProjectVersionCommands::Update {
+                    id_or_key,
+                    version_id,
+                    name,
+                    description,
+                    start_date,
+                    release_due_date,
+                    archived,
+                    json,
+                } => cmd::project::version::update(&ProjectVersionUpdateArgs::new(
+                    id_or_key,
+                    version_id,
+                    name,
+                    description,
+                    start_date,
+                    release_due_date,
+                    archived,
+                    json,
+                )),
+                ProjectVersionCommands::Delete {
+                    id_or_key,
+                    version_id,
+                    json,
+                } => cmd::project::version::delete(&ProjectVersionDeleteArgs::new(
+                    id_or_key, version_id, json,
+                )),
             },
         },
         Commands::Issue { action } => match action {
diff --git a/website/docs/commands.md b/website/docs/commands.md
index 8a79623..6f585d2 100644
--- a/website/docs/commands.md
+++ b/website/docs/commands.md
@@ -548,6 +548,72 @@ Example output:
 [4] Version 0.2 [archived]
 ```
 
+## `bl project version add`
+
+Add a version (milestone) to a project.
+
+```bash
+bl project version add <id-or-key> --name "v1.0"
+bl project version add <id-or-key> --name "v1.0" --start-date 2024-01-01 --release-due-date 2024-03-31
+bl project version add <id-or-key> --name "v1.0" --description "First release" --json
+```
+
+| Flag | Default | Description |
+| --- | --- | --- |
+| `--name` | — | Version name (required) |
+| `--description` | — | Description |
+| `--start-date` | — | Start date (YYYY-MM-DD) |
+| `--release-due-date` | — | Release due date (YYYY-MM-DD) |
+
+Example output:
+
+```text
+Added: [5] v1.0 (2024-01-01 → 2024-03-31)
+```
+
+## `bl project version update`
+
+Update a version in a project.
+
+```bash
+bl project version update <id-or-key> --version-id 5 --name "v1.0.1"
+bl project version update <id-or-key> --version-id 5 --name "v1.0" --archived true --json
+```
+
+| Flag | Default | Description |
+| --- | --- | --- |
+| `--version-id` | — | Version ID (required) |
+| `--name` | — | Version name (required) |
+| `--description` | — | Description |
+| `--start-date` | — | Start date (YYYY-MM-DD) |
+| `--release-due-date` | — | Release due date (YYYY-MM-DD) |
+| `--archived` | — | `true` to archive, `false` to unarchive |
+
+Example output:
+
+```text
+Updated: [5] v1.0.1 (2024-01-01 → 2024-03-31)
+```
+
+## `bl project version delete`
+
+Delete a version from a project.
+
+```bash
+bl project version delete <id-or-key> --version-id 5
+bl project version delete <id-or-key> --version-id 5 --json
+```
+
+| Flag | Default | Description |
+| --- | --- | --- |
+| `--version-id` | — | Version ID (required) |
+
+Example output:
+
+```text
+Deleted: [5] v1.0
+```
+
 ## `bl project create`
 
 Create a new project.
@@ -1432,9 +1498,9 @@ The table below maps Backlog API v2 endpoints to `bl` commands.
 | `bl project category update <id-or-key> --category-id <id>` | `PATCH /api/v2/projects/{projectIdOrKey}/categories/{id}` | ✅ Implemented |
 | `bl project category delete <id-or-key> --category-id <id>` | `DELETE /api/v2/projects/{projectIdOrKey}/categories/{id}` | ✅ Implemented |
 | `bl project version list <id-or-key>` | `GET /api/v2/projects/{projectIdOrKey}/versions` | ✅ Implemented |
-| `bl project version add <id-or-key>` | `POST /api/v2/projects/{projectIdOrKey}/versions` | Planned |
-| `bl project version update <id-or-key> <id>` | `PATCH /api/v2/projects/{projectIdOrKey}/versions/{id}` | Planned |
-| `bl project version delete <id-or-key> <id>` | `DELETE /api/v2/projects/{projectIdOrKey}/versions/{id}` | Planned |
+| `bl project version add <id-or-key>` | `POST /api/v2/projects/{projectIdOrKey}/versions` | ✅ Implemented |
+| `bl project version update <id-or-key> --version-id <id>` | `PATCH /api/v2/projects/{projectIdOrKey}/versions/{id}` | ✅ Implemented |
+| `bl project version delete <id-or-key> --version-id <id>` | `DELETE /api/v2/projects/{projectIdOrKey}/versions/{id}` | ✅ Implemented |
 | `bl project custom-field list <id-or-key>` | `GET /api/v2/projects/{projectIdOrKey}/customFields` | Planned |
 | `bl project custom-field add <id-or-key>` | `POST /api/v2/projects/{projectIdOrKey}/customFields` | Planned |
 | `bl project custom-field update <id-or-key> <id>` | `PATCH /api/v2/projects/{projectIdOrKey}/customFields/{id}` | Planned |
diff --git a/website/i18n/ja/docusaurus-plugin-content-docs/current/commands.md b/website/i18n/ja/docusaurus-plugin-content-docs/current/commands.md
index 23fd5cc..36f7dc3 100644
--- a/website/i18n/ja/docusaurus-plugin-content-docs/current/commands.md
+++ b/website/i18n/ja/docusaurus-plugin-content-docs/current/commands.md
@@ -548,6 +548,72 @@ bl project version list <id-or-key> --json
 [4] Version 0.2 [archived]
 ```
 
+## `bl project version add`
+
+プロジェクトにバージョン（マイルストーン）を追加します。
+
+```bash
+bl project version add <id-or-key> --name "v1.0"
+bl project version add <id-or-key> --name "v1.0" --start-date 2024-01-01 --release-due-date 2024-03-31
+bl project version add <id-or-key> --name "v1.0" --description "最初のリリース" --json
+```
+
+| フラグ | デフォルト | 説明 |
+| --- | --- | --- |
+| `--name` | — | バージョン名（必須） |
+| `--description` | — | 説明 |
+| `--start-date` | — | 開始日（YYYY-MM-DD） |
+| `--release-due-date` | — | リリース期限日（YYYY-MM-DD） |
+
+出力例:
+
+```text
+Added: [5] v1.0 (2024-01-01 → 2024-03-31)
+```
+
+## `bl project version update`
+
+プロジェクトのバージョンを更新します。
+
+```bash
+bl project version update <id-or-key> --version-id 5 --name "v1.0.1"
+bl project version update <id-or-key> --version-id 5 --name "v1.0" --archived true --json
+```
+
+| フラグ | デフォルト | 説明 |
+| --- | --- | --- |
+| `--version-id` | — | バージョン ID（必須） |
+| `--name` | — | バージョン名（必須） |
+| `--description` | — | 説明 |
+| `--start-date` | — | 開始日（YYYY-MM-DD） |
+| `--release-due-date` | — | リリース期限日（YYYY-MM-DD） |
+| `--archived` | — | `true` でアーカイブ、`false` で解除 |
+
+出力例:
+
+```text
+Updated: [5] v1.0.1 (2024-01-01 → 2024-03-31)
+```
+
+## `bl project version delete`
+
+プロジェクトからバージョンを削除します。
+
+```bash
+bl project version delete <id-or-key> --version-id 5
+bl project version delete <id-or-key> --version-id 5 --json
+```
+
+| フラグ | デフォルト | 説明 |
+| --- | --- | --- |
+| `--version-id` | — | バージョン ID（必須） |
+
+出力例:
+
+```text
+Deleted: [5] v1.0
+```
+
 ## `bl project create`
 
 新しいプロジェクトを作成します。
@@ -1436,9 +1502,9 @@ Backlog API v2 エンドポイントと `bl` コマンドの対応表です。
 | `bl project category update <id-or-key> --category-id <id>` | `PATCH /api/v2/projects/{projectIdOrKey}/categories/{id}` | ✅ 実装済み |
 | `bl project category delete <id-or-key> --category-id <id>` | `DELETE /api/v2/projects/{projectIdOrKey}/categories/{id}` | ✅ 実装済み |
 | `bl project version list <id-or-key>` | `GET /api/v2/projects/{projectIdOrKey}/versions` | ✅ 実装済み |
-| `bl project version add <id-or-key>` | `POST /api/v2/projects/{projectIdOrKey}/versions` | 計画中 |
-| `bl project version update <id-or-key> <id>` | `PATCH /api/v2/projects/{projectIdOrKey}/versions/{id}` | 計画中 |
-| `bl project version delete <id-or-key> <id>` | `DELETE /api/v2/projects/{projectIdOrKey}/versions/{id}` | 計画中 |
+| `bl project version add <id-or-key>` | `POST /api/v2/projects/{projectIdOrKey}/versions` | ✅ 実装済み |
+| `bl project version update <id-or-key> --version-id <id>` | `PATCH /api/v2/projects/{projectIdOrKey}/versions/{id}` | ✅ 実装済み |
+| `bl project version delete <id-or-key> --version-id <id>` | `DELETE /api/v2/projects/{projectIdOrKey}/versions/{id}` | ✅ 実装済み |
 | `bl project custom-field list <id-or-key>` | `GET /api/v2/projects/{projectIdOrKey}/customFields` | 計画中 |
 | `bl project custom-field add <id-or-key>` | `POST /api/v2/projects/{projectIdOrKey}/customFields` | 計画中 |
 | `bl project custom-field update <id-or-key> <id>` | `PATCH /api/v2/projects/{projectIdOrKey}/customFields/{id}` | 計画中 |