diff --git a/app/mailers/activity_mailer.rb b/app/mailers/activity_mailer.rb
index b21a6a6ff47..cd277e45ef5 100644
--- a/app/mailers/activity_mailer.rb
+++ b/app/mailers/activity_mailer.rb
@@ -306,9 +306,10 @@ def first_report(args = {})
   end
 
   # required params: answer, receiver
-  def chose_correct_answer
+  def chose_correct_answer(args = {})
+    @receiver ||= args[:receiver]
     @user = @receiver
-    @answer = params[:answer]
+    @answer = params&.key?(:answer) ? params[:answer] : args[:answer]
 
     @link_url = notification_redirector_url(
       link: question_path(@answer.question, anchor: "answer_#{@answer.id}"),
diff --git a/test/mailers/activity_mailer_test.rb b/test/mailers/activity_mailer_test.rb
index bb4ca47c9a7..45d10a3d0af 100644
--- a/test/mailers/activity_mailer_test.rb
+++ b/test/mailers/activity_mailer_test.rb
@@ -823,7 +823,25 @@ class ActivityMailerTest < ActionMailer::TestCase
     assert_match(/はじめて/, email.body.to_s)
   end
 
-  test 'chose_correct_answer' do
+  test 'chose_correct_answer with using synchronous mailer' do
+    answer = correct_answers(:correct_answer1)
+    receiver = answer.user
+
+    ActivityMailer.chose_correct_answer(
+      answer: answer,
+      receiver: receiver
+    ).deliver_now
+
+    assert_not ActionMailer::Base.deliveries.empty?
+    email = ActionMailer::Base.deliveries.last
+    query = CGI.escapeHTML({ kind: Notification.kinds[:chose_correct_answer], link: "/questions/#{answer.question.id}#answer_#{answer.id}" }.to_param)
+    assert_equal ['noreply@bootcamp.fjord.jp'], email.from
+    assert_equal [receiver.email], email.to
+    assert_equal "[FBC] #{answer.receiver.login_name}さんの質問【 #{answer.question.title} 】で#{answer.sender.login_name}さんの回答がベストアンサーに選ばれました。", email.subject
+    assert_match(%r{<a .+ href="http://localhost:3000/notification/redirector\?#{query}">回答へ</a>}, email.body.to_s)
+  end
+
+  test 'chose_correct_answer with params using asynchronous mailer' do
     answer = correct_answers(:correct_answer1)
     receiver = answer.user