diff --git a/apps/server/src/application/coordinators/startGameCoordinator.ts b/apps/server/src/application/coordinators/startGameCoordinator.ts
new file mode 100644
index 0000000..a4308fb
--- /dev/null
+++ b/apps/server/src/application/coordinators/startGameCoordinator.ts
@@ -0,0 +1,77 @@
+import { roomConsts } from "@repo/shared";
+import { GameManager } from "@server/domains/game/GameManager";
+import { type GameOutputPort } from "@server/domains/game/application/ports/gameUseCasePorts";
+import { startGameUseCase } from "@server/domains/game/application/useCases/startGameUseCase";
+import { RoomManager } from "@server/domains/room/RoomManager";
+import { logEvent } from "@server/logging/logEvent";
+
+type StartGameCoordinatorParams = {
+  ownerId: string;
+  gameManager: GameManager;
+  roomManager: RoomManager;
+  output: Pick<
+    GameOutputPort,
+    | "publishUpdatePlayerToRoom"
+    | "publishMapCellUpdatesToRoom"
+    | "publishGameEndToRoom"
+    | "publishGameStartToRoom"
+  >;
+};
+
+export const startGameCoordinator = ({
+  ownerId,
+  gameManager,
+  roomManager,
+  output,
+}: StartGameCoordinatorParams) => {
+  const room = roomManager.getRoomByOwnerId(ownerId);
+  if (!room) {
+    logEvent("GameUseCase", {
+      event: "START_GAME",
+      result: "ignored_no_room",
+      socketId: ownerId,
+    });
+    return;
+  }
+
+  if (room.status === roomConsts.RoomPhase.PLAYING) {
+    logEvent("GameUseCase", {
+      event: "START_GAME",
+      result: "ignored_already_playing",
+      roomId: room.roomId,
+      socketId: ownerId,
+    });
+    return;
+  }
+
+  const updatedRoom = roomManager.markRoomPlaying(room.roomId);
+  if (!updatedRoom) {
+    logEvent("GameUseCase", {
+      event: "START_GAME",
+      result: "ignored_room_not_found",
+      roomId: room.roomId,
+      socketId: ownerId,
+    });
+    return;
+  }
+
+  logEvent("GameUseCase", {
+    event: "START_GAME",
+    result: "accepted",
+    roomId: updatedRoom.roomId,
+    socketId: ownerId,
+    totalPlayers: updatedRoom.players.length,
+  });
+
+  const playerIds = updatedRoom.players.map((player) => player.id);
+
+  startGameUseCase({
+    roomId: updatedRoom.roomId,
+    playerIds,
+    gameManager,
+    onGameEnd: () => {
+      roomManager.markRoomWaiting(updatedRoom.roomId);
+    },
+    output,
+  });
+};
diff --git a/apps/server/src/domains/game/application/useCases/startGameUseCase.ts b/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
index e492412..0b853c8 100644
--- a/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
+++ b/apps/server/src/domains/game/application/useCases/startGameUseCase.ts
@@ -1,12 +1,11 @@
-import { roomConsts } from "@repo/shared";
-import { RoomManager } from "@server/domains/room/RoomManager";
 import type { GameOutputPort, StartGamePort } from "../ports/gameUseCasePorts";
 import { logEvent } from "@server/logging/logEvent";
 
 type StartGameUseCaseParams = {
-  ownerId: string;
+  roomId: string;
+  playerIds: string[];
   gameManager: StartGamePort;
-  roomManager: RoomManager;
+  onGameEnd: () => void;
   output: Pick<
     GameOutputPort,
     | "publishUpdatePlayerToRoom"
@@ -17,67 +16,36 @@
 };
 
 export const startGameUseCase = ({
-  ownerId,
+  roomId,
+  playerIds,
   gameManager,
-  roomManager,
+  onGameEnd,
   output,
 }: StartGameUseCaseParams) => {
-  const room = roomManager.getRoomByOwnerId(ownerId);
-  if (!room) {
-    logEvent("GameUseCase", {
-      event: "START_GAME",
-      result: "ignored_no_room",
-      socketId: ownerId,
-    });
-    return;
-  }
-
-  if (room.status === roomConsts.RoomPhase.PLAYING) {
-    logEvent("GameUseCase", {
-      event: "START_GAME",
-      result: "ignored_already_playing",
-      roomId: room.roomId,
-      socketId: ownerId,
-    });
-    return;
-  }
-
-  logEvent("GameUseCase", {
-    event: "START_GAME",
-    result: "accepted",
-    roomId: room.roomId,
-    socketId: ownerId,
-    totalPlayers: room.players.length,
-  });
-
-  room.status = roomConsts.RoomPhase.PLAYING;
-
-  const playerIds = room.players.map((p: { id: string }) => p.id);
-
   gameManager.startRoomSession(
-    room.roomId,
+    roomId,
     playerIds,
     (tickData) => {
       tickData.players.forEach((playerData) => {
-        output.publishUpdatePlayerToRoom(room.roomId, playerData);
+        output.publishUpdatePlayerToRoom(roomId, playerData);
       });
 
       if (tickData.cellUpdates.length > 0) {
-        output.publishMapCellUpdatesToRoom(room.roomId, tickData.cellUpdates);
+        output.publishMapCellUpdatesToRoom(roomId, tickData.cellUpdates);
       }
     },
     () => {
       logEvent("GameUseCase", {
         event: "GAME_END",
         result: "emitted",
-        roomId: room.roomId,
+        roomId,
         reason: "duration_elapsed",
       });
-      output.publishGameEndToRoom(room.roomId);
-      room.status = roomConsts.RoomPhase.WAITING;
+      output.publishGameEndToRoom(roomId);
+      onGameEnd();
     }
   );
 
-  const startTime = gameManager.getRoomStartTime(room.roomId) || Date.now();
-  output.publishGameStartToRoom(room.roomId, { startTime });
+  const startTime = gameManager.getRoomStartTime(roomId) || Date.now();
+  output.publishGameStartToRoom(roomId, { startTime });
 };
diff --git a/apps/server/src/domains/room/RoomManager.ts b/apps/server/src/domains/room/RoomManager.ts
index 4197846..47a86ed 100644
--- a/apps/server/src/domains/room/RoomManager.ts
+++ b/apps/server/src/domains/room/RoomManager.ts
@@ -3,6 +3,7 @@
  * ルーム状態の保持とルーム操作サービスへの委譲を担うマネージャ
  */
 import type { roomTypes } from "@repo/shared";
+import { roomConsts } from "@repo/shared";
 import { RoomJoinService } from "./application/services/RoomJoinService";
 import { RoomExitService } from "./application/services/RoomExitService";
 import { RoomQueryService } from "./application/services/RoomQueryService";
@@ -45,4 +46,26 @@
   public getRoomByPlayerId(playerId: string): roomTypes.Room | undefined {
     return this.roomQueryService.getRoomByPlayerId(playerId);
   }
+
+  // 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);
+    if (!room) {
+      return undefined;
+    }
+
+    room.status = roomConsts.RoomPhase.PLAYING;
+    return room;
+  }
+
+  // ルーム状態をWAITINGへ更新する
+  public markRoomWaiting(roomId: string): roomTypes.Room | undefined {
+    const room = this.roomQueryService.getRoomById(roomId);
+    if (!room) {
+      return undefined;
+    }
+
+    room.status = roomConsts.RoomPhase.WAITING;
+    return room;
+  }
 }
\ No newline at end of file
diff --git a/apps/server/src/network/handlers/game/registerGameHandlers.ts b/apps/server/src/network/handlers/game/registerGameHandlers.ts
index f64b1b0..bdd4cc0 100644
--- a/apps/server/src/network/handlers/game/registerGameHandlers.ts
+++ b/apps/server/src/network/handlers/game/registerGameHandlers.ts
@@ -7,13 +7,13 @@
 import { RoomManager } from "@server/domains/room/RoomManager";
 import { protocol } from "@repo/shared";
 import { pingUseCase } from "@server/domains/game/application/useCases/pingUseCase";
-import { startGameUseCase } from "@server/domains/game/application/useCases/startGameUseCase";
 import { readyForGameUseCase } from "@server/domains/game/application/useCases/readyForGameUseCase";
 import { movePlayerUseCase } from "@server/domains/game/application/useCases/movePlayerUseCase";
 import { createCommonHandlerContext } from "@server/network/handlers/CommonHandler";
 import { createGameOutputAdapter } from "./createGameOutputAdapter";
 import { logEvent } from "@server/logging/logEvent";
 import { isMovePayload, isPingPayload } from "@server/network/validation/socketPayloadValidators";
+import { startGameCoordinator } from "@server/application/coordinators/startGameCoordinator";
 
 /** 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 = (
@@ -44,7 +44,7 @@
 
   // オーナー開始要求に応じてゲーム進行ユースケースを起動する
   socket.on(protocol.SocketEvents.START_GAME, () => {
-    startGameUseCase({
+    startGameCoordinator({
       ownerId: socket.id,
       gameManager,
       roomManager,
diff --git a/test/load-bot.constants.ts b/test/load-bot.constants.ts
index 12216fd..61fae65 100644
--- a/test/load-bot.constants.ts
+++ b/test/load-bot.constants.ts
@@ -4,7 +4,7 @@
 
 export const URL = NETWORK_CONFIG.PROD_SERVER_URL;
 export const DEV_URL = NETWORK_CONFIG.DEV_SERVER_URL;
-export const BOTS = 20;
+export const BOTS = 10;
 export const DURATION_MS = Infinity;
 export const JOIN_DELAY_MS = 25;
 export const MOVE_TICK_MS = GAME_CONFIG.PLAYER_POSITION_UPDATE_MS;