diff --git a/admin/views/settings/space/space.model.html b/admin/views/settings/space/space.model.html
index 4911f571..ad044385 100644
--- a/admin/views/settings/space/space.model.html
+++ b/admin/views/settings/space/space.model.html
@@ -28,10 +28,10 @@
                 </div>
             </div>
             <div class="hr-line-dashed"></div>
-            <div class="form-group"><label class="col-sm-4 control-label">{{'SETTING.CONTACT' | translate}}</label>
+            <div class="form-group"><label class="col-sm-4 control-label">{{'SETTING.CONTACT' | translate}} ({{'SETTING.OPTIONAL' | translate}})</label>
                 <div class="col-sm-8">
                     <ui-select ng-model="space.contact.id" name="spacecontact" theme="bootstrap">
-                        <ui-select-match allow-clear="false" placeholder="{{'COMMON.PLACEHOLDER' | translate}}">
+                        <ui-select-match allow-clear="true" placeholder="{{'COMMON.PLACEHOLDER' | translate}}">
                             {{$select.selected.name}}</ui-select-match>
                         <ui-select-choices repeat="contact.id as contact in contacts | filter: $select.search">
                             <div ng-bind-html="contact.name | highlight: $select.search"></div>
diff --git a/myems-api/core/space.py b/myems-api/core/space.py
index c4831f25..f4838553 100644
--- a/myems-api/core/space.py
+++ b/myems-api/core/space.py
@@ -567,7 +567,7 @@ class SpaceItem:
                                    description='API.INVALID_IS_OUTPUT_COUNTED_VALUE')
         is_output_counted = new_values['data']['is_output_counted']
 
-        if 'contact_id' in new_values['data'].keys():
+        if 'contact_id' in new_values['data'].keys() and new_values['data']['contact_id'] is not None:
             if new_values['data']['contact_id'] <= 0:
                 raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                        description='API.INVALID_CONTACT_ID')
@@ -608,7 +608,7 @@ class SpaceItem:
         if cursor.fetchone() is not None:
             cursor.close()
             cnx.disconnect()
-            raise falcon.HTTPError(falcon.HTTP_404, title='API.BAD_REQUEST',
+            raise falcon.HTTPError(falcon.HTTP_400, title='API.BAD_REQUEST',
                                    description='API.SPACE_NAME_IS_ALREADY_IN_USE')
 
         if parent_space_id is not None: