diff --git a/src/main/java/jp/sf/fess/form/IndexForm.java b/src/main/java/jp/sf/fess/form/IndexForm.java
index 8d01cf20e..902fddf1f 100644
--- a/src/main/java/jp/sf/fess/form/IndexForm.java
+++ b/src/main/java/jp/sf/fess/form/IndexForm.java
@@ -61,7 +61,7 @@ public class IndexForm implements Serializable {
     @Maxbytelength(maxbytelength = 4000)
     public String rt;
 
-    @Required(target = "go")
+    @Required(target = "go,cache")
     @Maxbytelength(maxbytelength = 100)
     public String docId;