diff --git a/src/Eccube/Controller/Admin/Content/PageController.php b/src/Eccube/Controller/Admin/Content/PageController.php
index 48d7607feb9..b9f856d16f9 100644
--- a/src/Eccube/Controller/Admin/Content/PageController.php
+++ b/src/Eccube/Controller/Admin/Content/PageController.php
@@ -159,7 +159,12 @@ public function edit(Request $request, $id = null, Environment $twig, RouterInte
             if ($isUserDataPage) {
                 $templatePath = $this->getParameter('eccube_theme_user_data_dir');
             } else {
-                $templatePath = $this->getParameter('eccube_theme_front_dir');
+                if (preg_match('/^@/', $Page->getFileName(), $matches)) {
+                    // file_nameが@で始まる場合プラグインの名前空間とみなす
+                    $templatePath = $this->getParameter('eccube_theme_app_dir').'/plugin';
+                } else {
+                    $templatePath = $this->getParameter('eccube_theme_front_dir');
+                }
             }
             $filePath = $templatePath.'/'.$Page->getFileName().'.twig';
 
@@ -235,7 +240,12 @@ public function edit(Request $request, $id = null, Environment $twig, RouterInte
             $templatePath = $this->getParameter('eccube_theme_user_data_dir');
             $url = '';
         } else {
-            $templatePath = $this->getParameter('eccube_theme_front_dir');
+            if (preg_match('/^@/', $PrevPage->getFileName())) {
+                // file_nameが@で始まる場合プラグインの名前空間とみなす
+                $templatePath = $this->getParameter('eccube_theme_app_dir').'/plugin';
+            } else {
+                $templatePath = $this->getParameter('eccube_theme_front_dir');
+            }
             $url = $router->getRouteCollection()->get($PrevPage->getUrl())->getPath();
         }
         $projectDir = $this->getParameter('kernel.project_dir');
diff --git a/src/Eccube/Form/Type/Admin/MainEditType.php b/src/Eccube/Form/Type/Admin/MainEditType.php
index 9a41ef7bfea..a9de73f918f 100644
--- a/src/Eccube/Form/Type/Admin/MainEditType.php
+++ b/src/Eccube/Form/Type/Admin/MainEditType.php
@@ -101,7 +101,7 @@ public function buildForm(FormBuilderInterface $builder, array $options)
                         'max' => $this->eccubeConfig['eccube_stext_len'],
                     ]),
                     new Assert\Regex([
-                        'pattern' => '/^([0-9a-zA-Z_\-]+\/?)+$/',
+                        'pattern' => '/^@?([0-9a-zA-Z_\-]+\/?)+$/',
                     ]),
                 ],
             ])
diff --git a/src/Eccube/Resource/template/admin/Content/page_edit.twig b/src/Eccube/Resource/template/admin/Content/page_edit.twig
index 3d33dec3776..556404fe472 100644
--- a/src/Eccube/Resource/template/admin/Content/page_edit.twig
+++ b/src/Eccube/Resource/template/admin/Content/page_edit.twig
@@ -133,7 +133,7 @@ file that was distributed with this source code.
                                                 <div class="col-2 pl-0">.twig</div>
                                             {% else %}
                                                 <div class="col pr-0 align-middle">
-                                                    <span class="align-middle">{{ template_path }}/{{ form.file_name.vars.value }}.twig</span>
+                                                    <span class="align-middle">{{ template_path }}/{{ form.file_name.vars.value|replace({'@' : ''}) }}.twig</span>
                                                     <div>{{ form_widget(form.file_name, { type : 'hidden' } ) }}</div>
                                                 </div>
                                             {% endif %}