diff --git a/jpndlpy/client.py b/jpndlpy/client.py
index af96365..68eb3c8 100644
--- a/jpndlpy/client.py
+++ b/jpndlpy/client.py
@@ -86,15 +86,17 @@ def search_text(
         items : json
             複数の図書情報
         """
-
         data, errs = self.validation_serializer(kwargs)
-        if not errs:
+        if not errs and len(data) > 1:
             self.response = self.get(data)
             return self.response
         else:
-            erros_mes = ''.join(
-                [key + ' : ' + errs[key][0] + '\n' for key in errs]
-            )
+            if errs:
+                erros_mes = ''.join(
+                    [key + ' : ' + errs[key][0] + '\n' for key in errs]
+                )
+            else:
+                erros_mes = 'Missing data.'
             raise Exception(erros_mes)
 
     def validation_serializer(self, kwargs)->tuple:
diff --git a/jpndlpy/response.py b/jpndlpy/response.py
index deae18f..f918a1d 100644
--- a/jpndlpy/response.py
+++ b/jpndlpy/response.py
@@ -103,6 +103,8 @@ def extract_items(self, items):
         '''
         item情報を抽出する
         '''
+        if type(items) is not list:
+            items = [items]
         for item in items:
             """ Entity Object """
             item_object = ItemEntity()
diff --git a/jpndlpy/validator.py b/jpndlpy/validator.py
index 9643080..7fc3236 100644
--- a/jpndlpy/validator.py
+++ b/jpndlpy/validator.py
@@ -12,7 +12,7 @@
 class SearchTextSchema(Schema):
     dpid = fields.String()
     dpgroupid = fields.String()
-    title = fields.String(required=True)
+    title = fields.String()
     creator = fields.String()
     digitized_publisher = fields.String()
     ndc = fields.String()