diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index c91ae79..940a6c1 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -3,6 +3,7 @@
     package="org.ntlab.irisclient">
 
     <uses-permission android:name="android.permission.INTERNET" />
+    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 
     <application
         android:name=".Iris"
diff --git a/app/src/main/java/org/ntlab/irisclient/resources/RoomsRest.java b/app/src/main/java/org/ntlab/irisclient/resources/RoomsRest.java
index e31ed7b..381c08f 100644
--- a/app/src/main/java/org/ntlab/irisclient/resources/RoomsRest.java
+++ b/app/src/main/java/org/ntlab/irisclient/resources/RoomsRest.java
@@ -60,11 +60,12 @@
     //チーム変更、役職を変更するメソッド
     @FormUrlEncoded
     @PUT("rooms/{rid}/members/{nickname}")
-    Call<RoomJson> putMember(
+    Call<String> putMember(
             @Path("rid") String rid,
             @Path("nickname") String nickname,
             @Field("belongs") String belongs,
             @Field("is-master") boolean isMaster
+
     );
 
     //--------------------------------------------------
diff --git a/app/src/main/java/org/ntlab/irisclient/viewmodels/RoomViewModel.java b/app/src/main/java/org/ntlab/irisclient/viewmodels/RoomViewModel.java
index 480e7c8..ba4c58b 100644
--- a/app/src/main/java/org/ntlab/irisclient/viewmodels/RoomViewModel.java
+++ b/app/src/main/java/org/ntlab/irisclient/viewmodels/RoomViewModel.java
@@ -9,6 +9,7 @@
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.ViewModel;
 
+import java.io.Console;
 import java.util.List;
 
 import retrofit2.Call;
@@ -59,21 +60,24 @@
     }
 
     //-----------------------------------------------------------------------------
-    //Activityでのボタン処理
+    //各Activityでのボタン処理
     //チーム&マスター変更
     public void changeTeamAndMaster(String rid,String nickname,String belongs,Boolean isMaster) {
         final RoomsRest roomsRest = retrofit.create(RoomsRest.class);
-        Call<RoomJson> call = roomsRest.putMember(rid,nickname,belongs,isMaster);
+        Call<String> call = roomsRest.putMember(rid,nickname,belongs,isMaster);
 
-        call.enqueue(new Callback<RoomJson>() {
+        call.enqueue(new Callback<String>() {
             @Override
-            public void onResponse(Call<RoomJson> call, Response<RoomJson> response) {
+            public void onResponse(Call<String> call, Response<String> response) {
                 if (response.isSuccessful()){
-                    
+                    //サーバーで返り値変更しておく（String→void)
+                    //return 変更しましたの返り値がどう、とかいうエラー起きる
                 }
             }
             @Override
-            public void onFailure(Call<RoomJson> call, Throwable t) {
+            public void onFailure(Call<String> call, Throwable t) {
+                //System.out.println("通信失敗");
+                //System.out.println(t);
             }
         });
     }