diff --git a/css/admin.css b/css/admin.css
index c4d3b3b17..517c33dee 100644
--- a/css/admin.css
+++ b/css/admin.css
@@ -23523,4 +23523,8 @@ textarea[name=the_page_memo] {
   div.widget {
     margin: 0 !important;
   }
+}
+.taxonomy-post_tag .term-parent-wrap,
+.post-type-post .editor-post-taxonomies__hierarchical-terms-input + .components-base-control:has(#inspector-select-control-2) {
+  display: none;
 }
\ No newline at end of file
diff --git a/scss/admin.scss b/scss/admin.scss
index cbb258019..351c7520c 100644
--- a/scss/admin.scss
+++ b/scss/admin.scss
@@ -1115,4 +1115,11 @@ textarea[name="the_page_memo"]{
   div.widget {
     margin: 0 !important;
   }
+}
+
+//WordPressデフォルトのタグ（post_tag）一覧ページでは親を選択するドロップダウンを表示しない
+.taxonomy-post_tag .term-parent-wrap,
+//投稿ページのタグ選択画面では親を選択するドロップダウンを表示しない
+.post-type-post .editor-post-taxonomies__hierarchical-terms-input + .components-base-control:has(#inspector-select-control-2){
+  display: none;
 }
\ No newline at end of file