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 70ecb39..f8418bb 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
@@ -6,6 +6,7 @@
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.EditText;
+import android.widget.ImageButton;
 import androidx.activity.EdgeToEdge;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.graphics.Insets;
@@ -41,7 +42,7 @@
     senderMessage = findViewById(R.id.sender_message);
     receiverMessage = findViewById(R.id.receiver_message);
     sendButton = findViewById(R.id.send_Button);
-    backButton = findViewById(R.id.back_Button);
+    ImageButton backButton = findViewById(R.id.back_Button);
 
     receiverMessage.setKeyListener(null);//受信メッセージ編集不可
 
diff --git a/app/src/main/res/layout/activity_chat.xml b/app/src/main/res/layout/activity_chat.xml
index cdfad72..9a43176 100644
--- a/app/src/main/res/layout/activity_chat.xml
+++ b/app/src/main/res/layout/activity_chat.xml
@@ -56,8 +56,10 @@
     android:background="#E0F7FA"
     android:scaleType="fitCenter"
     app:srcCompat="@drawable/phone"
-    tools:layout_editor_absoluteX="5dp"
-    tools:layout_editor_absoluteY="5dp" />
+    app:layout_constraintStart_toStartOf="parent"
+    app:layout_constraintTop_toTopOf="parent"
+    android:layout_marginStart="5dp"
+    android:layout_marginTop="5dp" />
 
 
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file