diff --git a/apps/server/src/application/coordinators/disconnectCoordinator.ts b/apps/server/src/application/coordinators/disconnectCoordinator.ts
index 739dee6..fdcfc85 100644
--- a/apps/server/src/application/coordinators/disconnectCoordinator.ts
+++ b/apps/server/src/application/coordinators/disconnectCoordinator.ts
@@ -6,21 +6,13 @@
   type GameOutputPort,
 } from "@server/domains/game/application/ports/gameUseCasePorts";
 import type {
-  CleanupGameRuntimePort,
-  DisconnectRoomPort,
-  FindGameByPlayerPort,
-  FindRoomByIdPort,
-  FindRoomByPlayerPort,
+  DisconnectDeps,
   RoomOutputPort,
 } from "@server/domains/room/application/ports/roomUseCasePorts";
+import { resolveRuntimeByPlayerId } from "@server/domains/room/application/services/RoomRuntimeResolver";
 import { disconnectUseCase } from "@server/domains/game/application/useCases/disconnectUseCase";
 import { roomDisconnectUseCase } from "@server/domains/room/application/useCases/roomDisconnectUseCase";
 
-type DisconnectDeps = {
-  roomManager: DisconnectRoomPort & FindRoomByPlayerPort & FindRoomByIdPort;
-  runtimeRegistry: FindGameByPlayerPort & CleanupGameRuntimePort;
-};
-
 /** 切断調停で利用する入力ポートと出力ポートの契約 */
 export type DisconnectCoordinatorParams = {
   socketId: string;
@@ -37,13 +29,12 @@
   gameOutput,
   roomOutput,
 }: DisconnectCoordinatorParams) => {
-  const roomId = roomManager.getRoomByPlayerId(socketId)?.roomId;
-  const gameManager = runtimeRegistry.getGameManagerByPlayerId(socketId);
+  const runtime = resolveRuntimeByPlayerId(roomManager, runtimeRegistry, socketId);
 
-  if (gameManager) {
+  if (runtime) {
     disconnectUseCase({
-      gameManager,
-      roomId,
+      gameManager: runtime.gameManager,
+      roomId: runtime.roomId,
       playerId: socketId,
       output: gameOutput,
     });
diff --git a/apps/server/src/application/coordinators/readyForGameCoordinator.ts b/apps/server/src/application/coordinators/readyForGameCoordinator.ts
index 19fbd7c..68d8f44 100644
--- a/apps/server/src/application/coordinators/readyForGameCoordinator.ts
+++ b/apps/server/src/application/coordinators/readyForGameCoordinator.ts
@@ -5,14 +5,10 @@
 import {
   type GameOutputPort,
 } from "@server/domains/game/application/ports/gameUseCasePorts";
-import type { FindGameByPlayerPort, FindRoomByPlayerPort } from "@server/domains/room/application/ports/roomUseCasePorts";
+import type { ReadyForGameDeps } from "@server/domains/room/application/ports/roomUseCasePorts";
+import { resolveRuntimeByPlayerId } from "@server/domains/room/application/services/RoomRuntimeResolver";
 import { readyForGameUseCase } from "@server/domains/game/application/useCases/readyForGameUseCase";
 
-type ReadyForGameDeps = {
-  roomManager: FindRoomByPlayerPort;
-  runtimeRegistry: FindGameByPlayerPort;
-};
-
 type ReadyForGameCoordinatorParams = {
   socketId: string;
 } & ReadyForGameDeps & {
@@ -26,13 +22,12 @@
   runtimeRegistry,
   output,
 }: ReadyForGameCoordinatorParams) => {
-  const room = roomManager.getRoomByPlayerId(socketId);
-  const gameManager = runtimeRegistry.getGameManagerByPlayerId(socketId);
+  const runtime = resolveRuntimeByPlayerId(roomManager, runtimeRegistry, socketId);
 
   readyForGameUseCase({
     socketId,
-    roomId: room?.roomId,
-    gameManager,
+    roomId: runtime?.roomId,
+    gameManager: runtime?.gameManager,
     output,
   });
 };
diff --git a/apps/server/src/application/coordinators/startGameCoordinator.ts b/apps/server/src/application/coordinators/startGameCoordinator.ts
index d7c43e0..75198dd 100644
--- a/apps/server/src/application/coordinators/startGameCoordinator.ts
+++ b/apps/server/src/application/coordinators/startGameCoordinator.ts
@@ -6,20 +6,13 @@
   type GameOutputPort,
 } from "@server/domains/game/application/ports/gameUseCasePorts";
 import type {
-  FindGameByRoomPort,
-  FindRoomByOwnerPort,
-  RoomPhaseTransitionPort,
+  StartGameDeps,
 } from "@server/domains/room/application/ports/roomUseCasePorts";
 import { startGameUseCase } from "@server/domains/game/application/useCases/startGameUseCase";
 import { logEvent } from "@server/logging/logger";
 import { gameUseCaseLogEvents, logResults, logScopes } from "@server/logging/index";
 import { roomConsts } from "@repo/shared";
 
-type StartGameDeps = {
-  roomManager: FindRoomByOwnerPort & RoomPhaseTransitionPort;
-  runtimeRegistry: FindGameByRoomPort;
-};
-
 type StartGameCoordinatorParams = {
   ownerId: string;
 } & StartGameDeps & {
diff --git a/apps/server/src/domains/room/application/ports/roomUseCasePorts.ts b/apps/server/src/domains/room/application/ports/roomUseCasePorts.ts
index e87f5b0..034ee0d 100644
--- a/apps/server/src/domains/room/application/ports/roomUseCasePorts.ts
+++ b/apps/server/src/domains/room/application/ports/roomUseCasePorts.ts
@@ -11,6 +11,7 @@
   StartGamePort,
 } from "@server/domains/game/application/ports/gameUseCasePorts";
 
+/** ルーム単位ゲーム管理が満たす操作ポート集合 */
 export type RoomScopedGamePort =
   & StartGamePort
   & ReadyForGamePort
@@ -68,7 +69,7 @@
 
 /** ルーム解散後に不要ランタイムを破棄する操作ポート */
 export interface CleanupGameRuntimePort {
-  cleanupDisposedRoomRuntimes(): void;
+  cleanupGameManagerForRoom(roomId: string): void;
 }
 
 /** ルームIDでゲーム管理を解決する参照ポート */
@@ -80,3 +81,21 @@
 export interface FindGameByPlayerPort {
   getGameManagerByPlayerId(playerId: string): RoomScopedGamePort | undefined;
 }
+
+/** START_GAME調停で利用する依存集合 */
+export type StartGameDeps = {
+  roomManager: FindRoomByOwnerPort & RoomPhaseTransitionPort;
+  runtimeRegistry: FindGameByRoomPort;
+};
+
+/** READY_FOR_GAME調停で利用する依存集合 */
+export type ReadyForGameDeps = {
+  roomManager: FindRoomByPlayerPort;
+  runtimeRegistry: FindGameByPlayerPort;
+};
+
+/** DISCONNECT調停で利用する依存集合 */
+export type DisconnectDeps = {
+  roomManager: DisconnectRoomPort & FindRoomByPlayerPort & FindRoomByIdPort;
+  runtimeRegistry: FindGameByPlayerPort & CleanupGameRuntimePort;
+};
diff --git a/apps/server/src/domains/room/application/services/RoomGameRuntimeRegistry.ts b/apps/server/src/domains/room/application/services/RoomGameRuntimeRegistry.ts
index 390887f..20ca525 100644
--- a/apps/server/src/domains/room/application/services/RoomGameRuntimeRegistry.ts
+++ b/apps/server/src/domains/room/application/services/RoomGameRuntimeRegistry.ts
@@ -40,14 +40,17 @@
     return this.gameManagers.get(roomId);
   }
 
-  public cleanupDisposedRoomRuntimes(): void {
-    for (const [roomId, gameManager] of this.gameManagers.entries()) {
-      if (this.roomResolver.getRoomById(roomId)) {
-        continue;
-      }
-
-      gameManager.dispose();
-      this.gameManagers.delete(roomId);
+  public cleanupGameManagerForRoom(roomId: string): void {
+    if (this.roomResolver.getRoomById(roomId)) {
+      return;
     }
+
+    const gameManager = this.gameManagers.get(roomId);
+    if (!gameManager) {
+      return;
+    }
+
+    gameManager.dispose();
+    this.gameManagers.delete(roomId);
   }
 }
diff --git a/apps/server/src/domains/room/application/services/RoomRuntimeResolver.ts b/apps/server/src/domains/room/application/services/RoomRuntimeResolver.ts
new file mode 100644
index 0000000..85d3723
--- /dev/null
+++ b/apps/server/src/domains/room/application/services/RoomRuntimeResolver.ts
@@ -0,0 +1,33 @@
+/**
+ * RoomRuntimeResolver
+ * プレイヤーIDからルームIDとゲームランタイムを解決する
+ */
+import type {
+  FindGameByPlayerPort,
+  FindRoomByPlayerPort,
+  RoomScopedGamePort,
+} from "../ports/roomUseCasePorts";
+
+/** プレイヤー起点で解決したランタイム情報 */
+export type RuntimeByPlayerResolution = {
+  roomId: string;
+  gameManager: RoomScopedGamePort;
+};
+
+/** プレイヤーIDからルームIDとゲームランタイムを解決する */
+export const resolveRuntimeByPlayerId = (
+  roomResolver: FindRoomByPlayerPort,
+  runtimeResolver: FindGameByPlayerPort,
+  playerId: string
+): RuntimeByPlayerResolution | undefined => {
+  const roomId = roomResolver.getRoomByPlayerId(playerId)?.roomId;
+  const gameManager = runtimeResolver.getGameManagerByPlayerId(playerId);
+  if (!roomId || !gameManager) {
+    return undefined;
+  }
+
+  return {
+    roomId,
+    gameManager,
+  };
+};
diff --git a/apps/server/src/domains/room/application/useCases/roomDisconnectUseCase.ts b/apps/server/src/domains/room/application/useCases/roomDisconnectUseCase.ts
index 9d3c9ce..6c395ba 100644
--- a/apps/server/src/domains/room/application/useCases/roomDisconnectUseCase.ts
+++ b/apps/server/src/domains/room/application/useCases/roomDisconnectUseCase.ts
@@ -2,13 +2,18 @@
  * roomDisconnectUseCase
  * 切断時のルーム退出処理と状態更新配信を行うユースケース
  */
-import type { CleanupGameRuntimePort, DisconnectRoomPort } from "../ports/roomUseCasePorts";
+import type {
+  CleanupGameRuntimePort,
+  DisconnectRoomPort,
+  FindRoomByIdPort,
+  FindRoomByPlayerPort,
+} from "../ports/roomUseCasePorts";
 import type { RoomOutputPort } from "../ports/roomUseCasePorts";
 import { logEvent } from "@server/logging/logger";
 import { logResults, logScopes, roomUseCaseLogEvents } from "@server/logging/index";
 
 type RoomDisconnectUseCaseParams = {
-  roomManager: DisconnectRoomPort;
+  roomManager: DisconnectRoomPort & FindRoomByPlayerPort & FindRoomByIdPort;
   runtimeRegistry: CleanupGameRuntimePort;
   socketId: string;
   output: Pick<RoomOutputPort, "publishRoomUpdateToRoom">;
@@ -21,6 +26,7 @@
   socketId,
   output,
 }: RoomDisconnectUseCaseParams) => {
+  const beforeRoomId = roomManager.getRoomByPlayerId(socketId)?.roomId;
   const updatedRooms = roomManager.removePlayer(socketId);
   logEvent(logScopes.ROOM_USE_CASE, {
     event: roomUseCaseLogEvents.DISCONNECT,
@@ -41,5 +47,11 @@
     });
   });
 
-  runtimeRegistry.cleanupDisposedRoomRuntimes();
+  if (!beforeRoomId) {
+    return;
+  }
+
+  if (!roomManager.getRoomById(beforeRoomId)) {
+    runtimeRegistry.cleanupGameManagerForRoom(beforeRoomId);
+  }
 };
diff --git a/apps/server/src/network/handlers/game/registerGameHandlers.ts b/apps/server/src/network/handlers/game/registerGameHandlers.ts
index 97e40a9..83693f9 100644
--- a/apps/server/src/network/handlers/game/registerGameHandlers.ts
+++ b/apps/server/src/network/handlers/game/registerGameHandlers.ts
@@ -11,12 +11,12 @@
   FindGameByPlayerPort,
   FindRoomByOwnerPort,
   FindRoomByPlayerPort,
-  RoomScopedGamePort,
   RoomPhaseTransitionPort,
 } from "@server/domains/room/application/ports/roomUseCasePorts";
 import { movePlayerUseCase } from "@server/domains/game/application/useCases/movePlayerUseCase";
 import { placeBombUseCase } from "@server/domains/game/application/useCases/placeBombUseCase";
 import { pingUseCase } from "@server/domains/game/application/useCases/pingUseCase";
+import { resolveRuntimeByPlayerId } from "@server/domains/room/application/services/RoomRuntimeResolver";
 import { createCommonHandlerContext } from "@server/network/handlers/CommonHandler";
 import { isMovePayload, isPingPayload, isPlaceBombPayload } from "@server/network/validation/socketPayloadValidators";
 import { createServerSocketOnBridge } from "@server/network/handlers/socketEventBridge";
@@ -30,28 +30,6 @@
   [protocol.SocketEvents.PLACE_BOMB]: isPlaceBombPayload,
 } as const;
 
-type RuntimeResolution = {
-  roomId: string;
-  gameManager: RoomScopedGamePort;
-};
-
-const resolveRuntimeBySocketId = (
-  roomManager: FindRoomByPlayerPort,
-  runtimeRegistry: FindGameByPlayerPort,
-  socketId: string
-): RuntimeResolution | undefined => {
-  const roomId = roomManager.getRoomByPlayerId(socketId)?.roomId;
-  const gameManager = runtimeRegistry.getGameManagerByPlayerId(socketId);
-  if (!roomId || !gameManager) {
-    return undefined;
-  }
-
-  return {
-    roomId,
-    gameManager,
-  };
-};
-
 /** ゲームイベントの購読とユースケース呼び出しを設定する */
 export const registerGameHandlers = (
   io: Server,
@@ -113,7 +91,7 @@
       return;
     }
 
-    const runtime = resolveRuntimeBySocketId(roomManager, runtimeRegistry, socket.id);
+    const runtime = resolveRuntimeByPlayerId(roomManager, runtimeRegistry, socket.id);
     if (!runtime) {
       return;
     }
@@ -131,7 +109,7 @@
       return;
     }
 
-    const runtime = resolveRuntimeBySocketId(roomManager, runtimeRegistry, socket.id);
+    const runtime = resolveRuntimeByPlayerId(roomManager, runtimeRegistry, socket.id);
     if (!runtime) {
       return;
     }
diff --git a/apps/server/src/network/types/connectionPorts.ts b/apps/server/src/network/types/connectionPorts.ts
index ca79e45..dbaf4bc 100644
--- a/apps/server/src/network/types/connectionPorts.ts
+++ b/apps/server/src/network/types/connectionPorts.ts
@@ -5,6 +5,7 @@
 import type { Server } from "socket.io";
 import type {
   CleanupGameRuntimePort,
+  DisconnectDeps,
   DisconnectRoomPort,
   EnsureGameRuntimePort,
   FindGameByRoomPort,
@@ -29,24 +30,6 @@
   & FindGameByRoomPort
   & FindGameByPlayerPort;
 
-/** START_GAME調停で利用する依存集合 */
-export type StartGameDeps = {
-  roomManager: FindRoomByOwnerPort & RoomPhaseTransitionPort;
-  runtimeRegistry: FindGameByRoomPort;
-};
-
-/** READY_FOR_GAME調停で利用する依存集合 */
-export type ReadyForGameDeps = {
-  roomManager: FindRoomByPlayerPort;
-  runtimeRegistry: FindGameByPlayerPort;
-};
-
-/** DISCONNECT調停で利用する依存集合 */
-export type DisconnectDeps = {
-  roomManager: DisconnectRoomPort & FindRoomByPlayerPort & FindRoomByIdPort;
-  runtimeRegistry: FindGameByPlayerPort & CleanupGameRuntimePort;
-};
-
 /** ソケット接続全体で利用するルーム管理ポート集合 */
 export type SocketConnectionRoomPort =
   & ConnectionRoomPort