diff --git a/.idea/deploymentTargetSelector.xml b/.idea/deploymentTargetSelector.xml
index b268ef3..b0dfe32 100644
--- a/.idea/deploymentTargetSelector.xml
+++ b/.idea/deploymentTargetSelector.xml
@@ -4,6 +4,14 @@
     <selectionStates>
       <SelectionState runConfigName="app">
         <option name="selectionMode" value="DROPDOWN" />
+        <DropdownSelection timestamp="2025-12-13T11:47:16.629292500Z">
+          <Target type="DEFAULT_BOOT">
+            <handle>
+              <DeviceId pluginId="LocalEmulator" identifier="path=C:\Users\natsu\.android\avd\Pixel_8.avd" />
+            </handle>
+          </Target>
+        </DropdownSelection>
+        <DialogSelection />
       </SelectionState>
     </selectionStates>
   </component>
diff --git a/app/src/main/java/com/example/tampopo_client/views/ChatActivity.java b/app/src/main/java/com/example/tampopo_client/views/ChatActivity.java
index 73b36f7..769eb3c 100644
--- a/app/src/main/java/com/example/tampopo_client/views/ChatActivity.java
+++ b/app/src/main/java/com/example/tampopo_client/views/ChatActivity.java
@@ -47,6 +47,10 @@
     ChatViewModelFactory factory1 = new ChatViewModelFactory(tampopo.getUserId(), tampopo.getToken());
     chatViewModel = new ViewModelProvider(this, factory1).get(ChatViewModel.class);
     chatViewModel.setChatRoomId(tampopo.getChatroomId());
+    // チャット画面表示中はサーバーから最新メッセージを定期取得する
+    // 1秒ごとにChatViewModel.onUpdate()が呼ばれ、相手からのメッセージがあれば
+    // latestMessageLiveData経由でUIに反映される
+    chatViewModel.startUpdating(1L);
 
     senderMessage = findViewById(R.id.sender_message);
     receiverMessage = findViewById(R.id.receiver_message);