diff --git a/src/main/java/org/ntlab/citrusserver/resources/ScheduleRest.java b/src/main/java/org/ntlab/citrusserver/resources/ScheduleRest.java
index 7b349f0..5d08c8d 100644
--- a/src/main/java/org/ntlab/citrusserver/resources/ScheduleRest.java
+++ b/src/main/java/org/ntlab/citrusserver/resources/ScheduleRest.java
@@ -187,7 +187,8 @@
         if(accountManager.checkToken(accountId,token)) {
             int x=scheduleManager.setSchedulesBookId(accountId, year, month, day, scheduleId, bookId);
             if(x==-1){
-                return "その本は存在していません";
+                var response = Response.status(Response.Status.NOT_FOUND).entity("その本は存在しません");
+                throw new WebApplicationException(response.build());
             }else{
                 return "success";
             }