diff --git a/src/main/java/com/ntlab/irisserver/entities/DrawingController.java b/src/main/java/com/ntlab/irisserver/entities/DrawingController.java
index 0ef55d2..fec47bd 100644
--- a/src/main/java/com/ntlab/irisserver/entities/DrawingController.java
+++ b/src/main/java/com/ntlab/irisserver/entities/DrawingController.java
@@ -64,8 +64,11 @@
 
     //pathパラメーターを引数にするので、memberではなくてString
     //nicknameから書いてほしいdnoを返す
-    public int getDno(String nickname) {
+    public Integer getDno(String nickname) {
         Member mem = membersMap.get(nickname);
+        if(mem == null){
+            return null;
+        }
         List<Integer> dnoList = assignments.get(mem);
         int dno = dnoList.get(stage);
         return dno;