diff --git a/i18n/messages.ja.xml b/i18n/messages.ja.xml
index 24f46327f..c7b0096ca 100644
--- a/i18n/messages.ja.xml
+++ b/i18n/messages.ja.xml
@@ -82,10 +82,6 @@
         <source>Please input the below keyword.</source>
         <target>上に表示されているキーワードを入力してください。</target>
       </trans-unit>
-      <trans-unit id="">
-        <source>Invalid mobile_address.</source>
-        <target>メールアドレスが無効です。</target>
-      </trans-unit>
       <trans-unit id="">
         <source>Mon</source>
         <target>月</target>
diff --git a/lib/form/doctrine/MemberConfigForm.class.php b/lib/form/doctrine/MemberConfigForm.class.php
index a3546a585..87cc6434a 100644
--- a/lib/form/doctrine/MemberConfigForm.class.php
+++ b/lib/form/doctrine/MemberConfigForm.class.php
@@ -125,6 +125,8 @@ public function setMemberConfigWidget($name)
         'empty_value' => $this->validatorSchema[$name]->getOption('empty_value'),
       ));
 
+      $uniqueValidator->addMessage('duplicate', 'The inputted value is already exist.');
+
       $this->validatorSchema[$name] = new sfValidatorAnd(array(
         $this->validatorSchema[$name],
         $uniqueValidator,
@@ -229,7 +231,7 @@ public function isUnique($validator, $value, $arguments = array())
       return $value;
     }
 
-    throw new sfValidatorError($validator, 'Invalid %name%.', array('name' => $name));
+    throw new sfValidatorError($validator, 'duplicate');
   }
 
   public function isValid()