diff --git a/app/src/main/java/org/ntlab/irisclient/DrawingActivity.java b/app/src/main/java/org/ntlab/irisclient/DrawingActivity.java
index 8c4ca79..4764eab 100644
--- a/app/src/main/java/org/ntlab/irisclient/DrawingActivity.java
+++ b/app/src/main/java/org/ntlab/irisclient/DrawingActivity.java
@@ -99,9 +99,10 @@
     public void onClick(View v){
         if(v.getId() == R.id.okButtton) {//okButtonが押されたときの処理
 //            Bitmap bitmap = null;
-            drawingCanvas.setDrawingCacheEnabled(true);
+            drawingCanvas.setDrawingCacheEnabled(true);//キャッシュを取得する設定にする
             drawingCanvas.buildDrawingCache();
             Bitmap bitmap = Bitmap.createBitmap(drawingCanvas.getDrawingCache());
+            drawingCanvas.destroyDrawingCache();//既存のキャッシュをクリアする
             drawingStateViewModel.putDrawing(bitmap);
         }else if(v.getId() == R.id.clearButton){//clearButtonが押されたときの処理
             drawingCanvas.clearCanvas();