diff --git a/apps/web/src/app/tournament/[id]/create/_components/TournamentCreateClient.tsx b/apps/web/src/app/tournament/[id]/create/_components/TournamentCreateClient.tsx
index d0a34702..b1254a8a 100644
--- a/apps/web/src/app/tournament/[id]/create/_components/TournamentCreateClient.tsx
+++ b/apps/web/src/app/tournament/[id]/create/_components/TournamentCreateClient.tsx
@@ -99,6 +99,8 @@ function TournamentCreateClient({ tournamentId }: TournamentCreateClientProps) {
   // ownerStarted 면 어차피 시작 흐름으로 넘어가야 하므로 마감 처리하지 않는다.
   // 협업 의도가 없는 토너먼트는 만료 자체를 무시한다.
   const isDepositClosed = !tournamentData.isOwner && !ownerStarted && isExpired && isCollaborative;
+  // 참여자는 주최자가 시작한 뒤로 담을 수 없다(서버 409). 만료 마감과 별개 사유라 따로 둔다.
+  const isAddItemBlocked = isDepositClosed || (!tournamentData.isOwner && ownerStarted);
 
   const participantImageMap = new Map(
     (pending?.participants ?? []).map(p => [p.userId, p.profileImage])
@@ -195,7 +197,7 @@ function TournamentCreateClient({ tournamentId }: TournamentCreateClientProps) {
           items={pending?.items}
           scrollToLast={scrollToLast}
           previousItemCount={previousItemCount}
-          isDepositClosed={isDepositClosed}
+          isAddItemBlocked={isAddItemBlocked}
           participantImageMap={participantImageMap}
         />
         <TournamentItemBasketStatus
@@ -218,7 +220,8 @@ function TournamentCreateClient({ tournamentId }: TournamentCreateClientProps) {
         />
       </div>
 
-      <Dialog open={isGetItemDialogOpen} onOpenChange={setIsGetItemDialogOpen}>
+      {/* 쿼리 파라미터로 직접 열 수 있어 + 버튼과 같은 조건으로 막는다 */}
+      <Dialog open={isGetItemDialogOpen && !isAddItemBlocked} onOpenChange={setIsGetItemDialogOpen}>
         <GetItemDialogContent type="tournament" />
       </Dialog>
 
diff --git a/apps/web/src/app/tournament/[id]/create/_components/tournament-item-basket/TournamentItemBasket.tsx b/apps/web/src/app/tournament/[id]/create/_components/tournament-item-basket/TournamentItemBasket.tsx
index 29fc1449..730f7834 100644
--- a/apps/web/src/app/tournament/[id]/create/_components/tournament-item-basket/TournamentItemBasket.tsx
+++ b/apps/web/src/app/tournament/[id]/create/_components/tournament-item-basket/TournamentItemBasket.tsx
@@ -18,7 +18,7 @@ type TournamentItemBasketProps = {
   basketIndex: number;
   items: TournamentPendingItemT[];
   maxHeight?: number;
-  isDepositClosed?: boolean;
+  isAddItemBlocked?: boolean;
   participantImageMap?: Map<string, string>;
 };
 
@@ -26,7 +26,7 @@ function TournamentItemBasket({
   basketIndex,
   items,
   maxHeight,
-  isDepositClosed = false,
+  isAddItemBlocked = false,
   participantImageMap,
 }: TournamentItemBasketProps) {
   const { id } = useParams<{ id: string }>();
@@ -41,7 +41,7 @@ function TournamentItemBasket({
   };
 
   const isFull = items.length >= ITEMS_PER_BASKET;
-  const showAddButton = !isDepositClosed && !isFull;
+  const showAddButton = !isAddItemBlocked && !isFull;
 
   const addSlot = showAddButton ? (
     <Dialog>
diff --git a/apps/web/src/app/tournament/[id]/create/_components/tournament-item-basket/TournamentItemBasketCarousel.tsx b/apps/web/src/app/tournament/[id]/create/_components/tournament-item-basket/TournamentItemBasketCarousel.tsx
index 91bf972a..f317e61d 100644
--- a/apps/web/src/app/tournament/[id]/create/_components/tournament-item-basket/TournamentItemBasketCarousel.tsx
+++ b/apps/web/src/app/tournament/[id]/create/_components/tournament-item-basket/TournamentItemBasketCarousel.tsx
@@ -21,7 +21,7 @@ type TournamentItemBasketCarouselProps = {
   scrollToLast?: boolean;
   /** 위시 담기 등 재진입 시점의 기존 아이템 개수 */
   previousItemCount?: number | null;
-  isDepositClosed?: boolean;
+  isAddItemBlocked?: boolean;
   participantImageMap?: Map<string, string>;
 };
 
@@ -29,7 +29,7 @@ function TournamentItemBasketCarousel({
   items = [],
   scrollToLast = false,
   previousItemCount = null,
-  isDepositClosed = false,
+  isAddItemBlocked = false,
   participantImageMap,
 }: TournamentItemBasketCarouselProps) {
   const [carouselApi, setCarouselApi] = useState<CarouselApi>();
@@ -116,7 +116,7 @@ function TournamentItemBasketCarousel({
         <TournamentItemBasket
           basketIndex={0}
           items={items}
-          isDepositClosed={isDepositClosed}
+          isAddItemBlocked={isAddItemBlocked}
           maxHeight={basketMaxHeight}
           participantImageMap={participantImageMap}
         />
@@ -145,7 +145,7 @@ function TournamentItemBasketCarousel({
               <TournamentItemBasket
                 basketIndex={i}
                 items={items.slice(i * ITEMS_PER_BASKET, (i + 1) * ITEMS_PER_BASKET)}
-                isDepositClosed={isDepositClosed}
+                isAddItemBlocked={isAddItemBlocked}
                 maxHeight={basketMaxHeight}
                 participantImageMap={participantImageMap}
               />