diff --git a/backend/app/Http/Controllers/Api/MeetingsController.php b/backend/app/Http/Controllers/Api/MeetingsController.php
index 3f9fbb80..a44d6b54 100644
--- a/backend/app/Http/Controllers/Api/MeetingsController.php
+++ b/backend/app/Http/Controllers/Api/MeetingsController.php
@@ -501,6 +501,16 @@ class MeetingsController extends Controller {
             'memo' => 'nullable|max:2000',
         ]);
 
+        // ミームタイプ
+        Validator::extend('pdf_meme', function ($attribute, $value, $params, $validator) {
+            try {
+                return mime_content_type($value) == 'application/pdf';
+            } catch (\Throwable $e) {
+                Log::critical($e->getMessage());
+                return false;
+            }
+        });
+
         if ($validate->fails()) {
             return ['status_code' => 422, 'error_messages' => $validate->errors()];
         }
@@ -517,6 +527,13 @@ class MeetingsController extends Controller {
                 $filename = uniqid() . '.pdf';
                 $pdf = base64_decode(substr($r->pdf, strpos($r->pdf, ',') + 1));
                 $update['pdf'] = '/storage/'.$filename;
+
+                if ($chk = Meeting::select('pdf')->where('id', (int)$meeting_id)->first()) {
+                    if (Storage::disk('public')->has($chk->pdf)) {
+                        Storage::disk('public')->delete($chk->pdf);
+                    }
+                }
+
                 Storage::disk('public')->put($filename, $pdf);
             }
 
diff --git a/backend/resources/lang/ja/validation.php b/backend/resources/lang/ja/validation.php
index 959159db..ed8043a1 100644
--- a/backend/resources/lang/ja/validation.php
+++ b/backend/resources/lang/ja/validation.php
@@ -106,6 +106,7 @@ return [
     'required_with_all' => 'The :attribute field is required when :values are present.',
     'required_without' => 'The :attribute field is required when :values is not present.',
     'required_without_all' => 'The :attribute field is required when none of :values are present.',
+    'pdf_meme' => 'ファイル形式はpdfのみです。',
     'prohibited' => 'The :attribute field is prohibited.',
     'prohibited_if' => 'The :attribute field is prohibited when :other is :value.',
     'prohibited_unless' => 'The :attribute field is prohibited unless :other is in :values.',