diff --git a/app/src/main/java/org/ntlab/irisclient/DrawingActivity.java b/app/src/main/java/org/ntlab/irisclient/DrawingActivity.java
index febdbf1..d255f4a 100644
--- a/app/src/main/java/org/ntlab/irisclient/DrawingActivity.java
+++ b/app/src/main/java/org/ntlab/irisclient/DrawingActivity.java
@@ -10,6 +10,7 @@
 import android.os.Bundle;
 import android.view.View;
 import android.widget.CompoundButton;
+import android.widget.SeekBar;
 import android.widget.TextView;
 import android.widget.ToggleButton;
 
@@ -71,10 +72,28 @@
             }
         });
 
+        //筆の大きさを変えるシークバー
+        SeekBar seekbar = findViewById(R.id.seekBar);
+        seekbar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
+            @Override
+            public void onProgressChanged(SeekBar seekBar, int i, boolean b) {//変更中
+                drawingCanvas.setPenWidth(i);
+            }
+
+            @Override
+            public void onStartTrackingTouch(SeekBar seekBar) {//変更開始時
+            }
+
+            @Override
+            public void onStopTrackingTouch(SeekBar seekBar) {//変更終了時
+            }
+        });
+
 
         TextView textKeyword =(TextView)findViewById(R.id.keywordText);//keywordのTextView
         TextView textMemberNum = (TextView)findViewById(R.id.drawingNowText);//残りのイラスト枚数のTextView
         TextView timerText = (TextView)findViewById(R.id.timerText);//TimerのTextView
+
         drawingCanvas = (DrawingCanvas) findViewById(R.id.drawingCanvas);
 
         //残りのイラスト枚数の表示
@@ -119,7 +138,7 @@
             }
         });
 
-        //getTimier
+        //getTimer
         drawingStateViewModel.getTimer().observe(this, new Observer<Integer>(){
             @Override
             public void onChanged(Integer time) {