diff --git a/apps/server/src/application/coordinators/disconnectCoordinator.ts b/apps/server/src/application/coordinators/disconnectCoordinator.ts
index 71d0884..47df6fe 100644
--- a/apps/server/src/application/coordinators/disconnectCoordinator.ts
+++ b/apps/server/src/application/coordinators/disconnectCoordinator.ts
@@ -6,6 +6,7 @@
   type GameOutputPort,
 } from "@server/domains/game/application/ports/gameUseCasePorts";
 import type {
+  CleanupGameRuntimePort,
   DisconnectRoomPort,
   FindGameByPlayerPort,
   FindRoomByIdPort,
@@ -18,7 +19,8 @@
 /** 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;
-  roomManager: DisconnectRoomPort & FindRoomByPlayerPort & FindRoomByIdPort & FindGameByPlayerPort;
+  roomManager: DisconnectRoomPort & FindRoomByPlayerPort & FindRoomByIdPort;
+  runtimeRegistry: FindGameByPlayerPort & CleanupGameRuntimePort;
   gameOutput: Pick<GameOutputPort, "publishPlayerRemovedToRoom">;
   roomOutput: Pick<RoomOutputPort, "publishRoomUpdateToRoom">;
 };
@@ -27,11 +29,12 @@
 export const disconnectCoordinator = ({
   socketId,
   roomManager,
+  runtimeRegistry,
   gameOutput,
   roomOutput,
 }: DisconnectCoordinatorParams) => {
   const roomId = roomManager.getRoomByPlayerId(socketId)?.roomId;
-  const gameManager = roomManager.getGameManagerByPlayerId(socketId);
+  const gameManager = runtimeRegistry.getGameManagerByPlayerId(socketId);
 
   if (gameManager) {
     disconnectUseCase({
@@ -47,4 +50,6 @@
     socketId,
     output: roomOutput,
   });
+
+  runtimeRegistry.cleanupDisposedRoomRuntimes();
 };
diff --git a/apps/server/src/application/coordinators/readyForGameCoordinator.ts b/apps/server/src/application/coordinators/readyForGameCoordinator.ts
index 8c1acc8..0f64720 100644
--- a/apps/server/src/application/coordinators/readyForGameCoordinator.ts
+++ b/apps/server/src/application/coordinators/readyForGameCoordinator.ts
@@ -10,7 +10,8 @@
 
 type ReadyForGameCoordinatorParams = {
   socketId: string;
-  roomManager: FindRoomByPlayerPort & FindGameByPlayerPort;
+  roomManager: FindRoomByPlayerPort;
+  runtimeRegistry: FindGameByPlayerPort;
   output: Pick<GameOutputPort, "publishCurrentPlayersToSocket" | "publishGameStartToSocket">;
 };
 
@@ -18,10 +19,11 @@
 export const readyForGameCoordinator = ({
   socketId,
   roomManager,
+  runtimeRegistry,
   output,
 }: ReadyForGameCoordinatorParams) => {
   const room = roomManager.getRoomByPlayerId(socketId);
-  const gameManager = roomManager.getGameManagerByPlayerId(socketId);
+  const gameManager = runtimeRegistry.getGameManagerByPlayerId(socketId);
 
   readyForGameUseCase({
     socketId,
diff --git a/apps/server/src/application/coordinators/startGameCoordinator.ts b/apps/server/src/application/coordinators/startGameCoordinator.ts
index 2bc6080..e5143d9 100644
--- a/apps/server/src/application/coordinators/startGameCoordinator.ts
+++ b/apps/server/src/application/coordinators/startGameCoordinator.ts
@@ -17,7 +17,8 @@
 
 type StartGameCoordinatorParams = {
   ownerId: string;
-  roomManager: FindRoomByOwnerPort & RoomPhaseTransitionPort & FindGameByRoomPort;
+  roomManager: FindRoomByOwnerPort & RoomPhaseTransitionPort;
+  runtimeRegistry: FindGameByRoomPort;
   output: Pick<
     GameOutputPort,
     | "publishUpdatePlayersToSocket"
@@ -32,6 +33,7 @@
 export const startGameCoordinator = ({
   ownerId,
   roomManager,
+  runtimeRegistry,
   output,
 }: StartGameCoordinatorParams) => {
   const room = roomManager.getRoomByOwnerId(ownerId);
@@ -74,7 +76,7 @@
   });
 
   const playerIds = updatedRoom.players.map((player) => player.id);
-  const gameManager = roomManager.getGameManagerByRoomId(updatedRoom.roomId);
+  const gameManager = runtimeRegistry.getGameManagerByRoomId(updatedRoom.roomId);
   if (!gameManager) {
     return;
   }
diff --git a/apps/server/src/domains/room/RoomManager.ts b/apps/server/src/domains/room/RoomManager.ts
index ed8c4a6..47a86ed 100644
--- a/apps/server/src/domains/room/RoomManager.ts
+++ b/apps/server/src/domains/room/RoomManager.ts
@@ -4,7 +4,6 @@
  */
 import type { roomTypes } from "@repo/shared";
 import { roomConsts } from "@repo/shared";
-import { GameManager } from "@server/domains/game/GameManager";
 import { RoomJoinService } from "./application/services/RoomJoinService";
 import { RoomExitService } from "./application/services/RoomExitService";
 import { RoomQueryService } from "./application/services/RoomQueryService";
@@ -13,7 +12,6 @@
 /** ルーム操作の公開インターフェースを提供するマネージャ */
 export class RoomManager {
   private rooms: Map<string, roomTypes.Room> = new Map();
-  private gameManagers: Map<string, GameManager> = new Map();
   private roomJoinService: RoomJoinService;
   private roomExitService: RoomExitService;
   private roomQueryService: RoomQueryService;
@@ -26,20 +24,12 @@
 
   // ルームにプレイヤーを追加する，ルームが未作成なら新規作成する
   public addPlayerToRoom(roomId: string, socketId: string, playerName: string): JoinRoomResult {
-    const joinResult = this.roomJoinService.addPlayerToRoom(roomId, socketId, playerName);
-
-    if (joinResult.status === "joined" && !this.gameManagers.has(roomId)) {
-      this.gameManagers.set(roomId, new GameManager(roomId));
-    }
-
-    return joinResult;
+    return this.roomJoinService.addPlayerToRoom(roomId, socketId, playerName);
   }
 
   // プレイヤーをルームから削除し，更新が発生したルーム配列を返す
   public removePlayer(socketId: string): roomTypes.Room[] {
-    const updatedRooms = this.roomExitService.removePlayer(socketId);
-    this.cleanupDisposedRooms();
-    return updatedRooms;
+    return this.roomExitService.removePlayer(socketId);
   }
 
   // オーナーIDからルームを取得する
@@ -57,19 +47,6 @@
     return this.roomQueryService.getRoomByPlayerId(playerId);
   }
 
-  public getGameManagerByRoomId(roomId: string): GameManager | undefined {
-    return this.gameManagers.get(roomId);
-  }
-
-  public getGameManagerByPlayerId(playerId: string): GameManager | undefined {
-    const roomId = this.roomQueryService.getRoomByPlayerId(playerId)?.roomId;
-    if (!roomId) {
-      return undefined;
-    }
-
-    return this.gameManagers.get(roomId);
-  }
-
   // ルーム状態をPLAYINGへ更新する
   public markRoomPlaying(roomId: string): roomTypes.Room | undefined {
     const room = this.roomQueryService.getRoomById(roomId);
@@ -91,15 +68,4 @@
     room.status = roomConsts.RoomPhase.WAITING;
     return room;
   }
-
-  private cleanupDisposedRooms(): void {
-    for (const [roomId, gameManager] of this.gameManagers.entries()) {
-      if (this.rooms.has(roomId)) {
-        continue;
-      }
-
-      gameManager.dispose();
-      this.gameManagers.delete(roomId);
-    }
-  }
 }
\ No newline at end of file
diff --git a/apps/server/src/domains/room/application/ports/roomUseCasePorts.ts b/apps/server/src/domains/room/application/ports/roomUseCasePorts.ts
index 7702349..e87f5b0 100644
--- a/apps/server/src/domains/room/application/ports/roomUseCasePorts.ts
+++ b/apps/server/src/domains/room/application/ports/roomUseCasePorts.ts
@@ -61,6 +61,16 @@
   getRoomById(roomId: string): roomTypes.Room | undefined;
 }
 
+/** ルーム参加後にゲームランタイムを確保する操作ポート */
+export interface EnsureGameRuntimePort {
+  ensureGameManagerForRoom(roomId: string): void;
+}
+
+/** 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;
+}
+
 /** ルームIDでゲーム管理を解決する参照ポート */
 export interface FindGameByRoomPort {
   getGameManagerByRoomId(roomId: string): RoomScopedGamePort | undefined;
diff --git a/apps/server/src/domains/room/application/services/RoomGameRuntimeRegistry.ts b/apps/server/src/domains/room/application/services/RoomGameRuntimeRegistry.ts
new file mode 100644
index 0000000..390887f
--- /dev/null
+++ b/apps/server/src/domains/room/application/services/RoomGameRuntimeRegistry.ts
@@ -0,0 +1,53 @@
+/**
+ * RoomGameRuntimeRegistry
+ * ルーム単位のゲームランタイム生成，解決，破棄を管理する
+ */
+import { GameManager } from "@server/domains/game/GameManager";
+import type {
+  CleanupGameRuntimePort,
+  EnsureGameRuntimePort,
+  FindGameByPlayerPort,
+  FindGameByRoomPort,
+  FindRoomByIdPort,
+  FindRoomByPlayerPort,
+} from "../ports/roomUseCasePorts";
+
+/** ルームIDごとのゲームランタイムを管理するレジストリ */
+export class RoomGameRuntimeRegistry
+  implements EnsureGameRuntimePort, CleanupGameRuntimePort, FindGameByRoomPort, FindGameByPlayerPort {
+  private gameManagers: Map<string, GameManager> = new Map();
+
+  constructor(private roomResolver: FindRoomByPlayerPort & FindRoomByIdPort) {}
+
+  public ensureGameManagerForRoom(roomId: string): void {
+    if (this.gameManagers.has(roomId)) {
+      return;
+    }
+
+    this.gameManagers.set(roomId, new GameManager(roomId));
+  }
+
+  public getGameManagerByRoomId(roomId: string): GameManager | undefined {
+    return this.gameManagers.get(roomId);
+  }
+
+  public getGameManagerByPlayerId(playerId: string): GameManager | undefined {
+    const roomId = this.roomResolver.getRoomByPlayerId(playerId)?.roomId;
+    if (!roomId) {
+      return undefined;
+    }
+
+    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);
+    }
+  }
+}
diff --git a/apps/server/src/network/SocketManager.ts b/apps/server/src/network/SocketManager.ts
index a0c4ee0..2498bdf 100644
--- a/apps/server/src/network/SocketManager.ts
+++ b/apps/server/src/network/SocketManager.ts
@@ -6,6 +6,7 @@
 import type {
   SocketConnectionManagerBundle,
   SocketConnectionRoomPort,
+  SocketConnectionRuntimePort,
 } from "./types/connectionPorts";
 import { registerConnectionHandlers } from "./handlers/registerConnectionHandlers";
 
@@ -16,11 +17,13 @@
 
   constructor(
     io: Server,
-    roomManager: SocketConnectionRoomPort
+    roomManager: SocketConnectionRoomPort,
+    runtimeRegistry: SocketConnectionRuntimePort
   ) {
     this.io = io;
     this.managers = {
       roomManager,
+      runtimeRegistry,
     };
   }
 
diff --git a/apps/server/src/network/bootstrap/boot.ts b/apps/server/src/network/bootstrap/boot.ts
index 130d54d..1da296a 100644
--- a/apps/server/src/network/bootstrap/boot.ts
+++ b/apps/server/src/network/bootstrap/boot.ts
@@ -4,6 +4,7 @@
  */
 import type { Server as HttpServer } from "http";
 import { RoomManager } from "@server/domains/room/RoomManager";
+import { RoomGameRuntimeRegistry } from "@server/domains/room/application/services/RoomGameRuntimeRegistry";
 import { SocketManager } from "../SocketManager";
 import { createIo } from "./createIo";
 
@@ -12,7 +13,8 @@
   // ネットワーク層とドメイン層の依存を構築する
   const io = createIo(httpServer);
   const roomManager = new RoomManager();
-  const socketManager = new SocketManager(io, roomManager);
+  const runtimeRegistry = new RoomGameRuntimeRegistry(roomManager);
+  const socketManager = new SocketManager(io, roomManager, runtimeRegistry);
 
   socketManager.initialize();
 };
diff --git a/apps/server/src/network/handlers/game/registerGameHandlers.ts b/apps/server/src/network/handlers/game/registerGameHandlers.ts
index 6d3db79..90f5996 100644
--- a/apps/server/src/network/handlers/game/registerGameHandlers.ts
+++ b/apps/server/src/network/handlers/game/registerGameHandlers.ts
@@ -33,7 +33,8 @@
 export const registerGameHandlers = (
   io: Server,
   socket: Socket,
-  roomManager: FindRoomByOwnerPort & FindRoomByPlayerPort & RoomPhaseTransitionPort & FindGameByRoomPort & FindGameByPlayerPort
+  roomManager: FindRoomByOwnerPort & FindRoomByPlayerPort & RoomPhaseTransitionPort,
+  runtimeRegistry: FindGameByRoomPort & FindGameByPlayerPort
 ) => {
   const common = createCommonHandlerContext(io, socket);
   const gameOutputAdapter = createGameOutputAdapter(common);
@@ -68,6 +69,7 @@
     startGameCoordinator({
       ownerId: socket.id,
       roomManager,
+      runtimeRegistry,
       output: gameOutputAdapter,
     });
   });
@@ -77,6 +79,7 @@
     readyForGameCoordinator({
       socketId: socket.id,
       roomManager,
+      runtimeRegistry,
       output: gameOutputAdapter,
     });
   });
@@ -87,7 +90,7 @@
       return;
     }
 
-    const gameManager = roomManager.getGameManagerByPlayerId(socket.id);
+    const gameManager = runtimeRegistry.getGameManagerByPlayerId(socket.id);
     if (!gameManager) {
       return;
     }
@@ -106,7 +109,7 @@
     }
 
     const roomId = roomManager.getRoomByPlayerId(socket.id)?.roomId;
-    const gameManager = roomManager.getGameManagerByPlayerId(socket.id);
+    const gameManager = runtimeRegistry.getGameManagerByPlayerId(socket.id);
     if (!roomId || !gameManager) {
       return;
     }
diff --git a/apps/server/src/network/handlers/registerConnectionHandlers.ts b/apps/server/src/network/handlers/registerConnectionHandlers.ts
index 35e602a..e4fccca 100644
--- a/apps/server/src/network/handlers/registerConnectionHandlers.ts
+++ b/apps/server/src/network/handlers/registerConnectionHandlers.ts
@@ -19,6 +19,7 @@
 export const registerConnectionHandlers = ({
   io,
   roomManager,
+  runtimeRegistry,
 }: RegisterConnectionHandlersParams) => {
   const gameDisconnectOutputAdapter = createGameDisconnectOutputAdapter(io);
   const roomDisconnectOutputAdapter = createRoomDisconnectOutputAdapter(io);
@@ -31,8 +32,8 @@
       socketId: socket.id,
     });
 
-    registerRoomHandlers(io, socket, roomManager);
-    registerGameHandlers(io, socket, roomManager);
+    registerRoomHandlers(io, socket, roomManager, runtimeRegistry);
+    registerGameHandlers(io, socket, roomManager, runtimeRegistry);
 
     socket.on(protocol.SocketEvents.DISCONNECT, () => {
       // 切断ログ記録後にドメイン別の後処理を実行する
@@ -45,6 +46,7 @@
       disconnectCoordinator({
         socketId: socket.id,
         roomManager,
+        runtimeRegistry,
         gameOutput: gameDisconnectOutputAdapter,
         roomOutput: roomDisconnectOutputAdapter,
       });
diff --git a/apps/server/src/network/handlers/room/registerRoomHandlers.ts b/apps/server/src/network/handlers/room/registerRoomHandlers.ts
index 3f1e989..db1b83c 100644
--- a/apps/server/src/network/handlers/room/registerRoomHandlers.ts
+++ b/apps/server/src/network/handlers/room/registerRoomHandlers.ts
@@ -4,7 +4,10 @@
  */
 import { Server, Socket } from "socket.io";
 import { protocol } from "@repo/shared";
-import type { JoinRoomPort } from "@server/domains/room/application/ports/roomUseCasePorts";
+import type {
+  EnsureGameRuntimePort,
+  JoinRoomPort,
+} from "@server/domains/room/application/ports/roomUseCasePorts";
 import { joinRoomUseCase } from "@server/domains/room/application/useCases/joinRoomUseCase";
 import { logEvent } from "@server/logging/logger";
 import { logResults, logScopes } from "@server/logging/index";
@@ -23,7 +26,8 @@
 export const registerRoomHandlers = (
   io: Server,
   socket: Socket,
-  roomManager: JoinRoomPort
+  roomManager: JoinRoomPort,
+  runtimeRegistry: EnsureGameRuntimePort
 ) => {
   const common = createCommonHandlerContext(io, socket);
   const roomOutputAdapter = createRoomOutputAdapter(common);
@@ -70,6 +74,7 @@
         return;
 
       case "joined":
+        runtimeRegistry.ensureGameManagerForRoom(roomId);
         await socket.join(roomId);
         roomOutputAdapter.publishRoomUpdateToRoom(roomId, joinResult.room);
         logEvent(logScopes.ROOM_USE_CASE, {
diff --git a/apps/server/src/network/types/connectionPorts.ts b/apps/server/src/network/types/connectionPorts.ts
index f5dce4c..2b1f4a2 100644
--- a/apps/server/src/network/types/connectionPorts.ts
+++ b/apps/server/src/network/types/connectionPorts.ts
@@ -4,7 +4,9 @@
  */
 import type { Server } from "socket.io";
 import type {
+  CleanupGameRuntimePort,
   DisconnectRoomPort,
+  EnsureGameRuntimePort,
   FindGameByRoomPort,
   FindGameByPlayerPort,
   FindRoomByOwnerPort,
@@ -19,7 +21,11 @@
   & JoinRoomPort
   & FindRoomByOwnerPort
   & FindRoomByPlayerPort
-  & RoomPhaseTransitionPort
+  & RoomPhaseTransitionPort;
+
+/** 接続時のゲームランタイム解決で利用する入力ポート集合 */
+export type ConnectionRuntimePort =
+  & EnsureGameRuntimePort
   & FindGameByRoomPort
   & FindGameByPlayerPort;
 
@@ -29,9 +35,15 @@
   & DisconnectRoomPort
   & FindRoomByIdPort;
 
+/** ソケット接続全体で利用するランタイム管理ポート集合 */
+export type SocketConnectionRuntimePort =
+  & ConnectionRuntimePort
+  & CleanupGameRuntimePort;
+
 /** ソケット接続ハンドラで受け取るマネージャ依存の束 */
 export type SocketConnectionManagerBundle = {
   roomManager: SocketConnectionRoomPort;
+  runtimeRegistry: SocketConnectionRuntimePort;
 };
 
 /** 接続ハンドラ登録関数が受け取る入力パラメータ */