diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 7944f9f..1671234 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -1,4 +1,11 @@
 # frozen_string_literal: true
 
 class ApplicationController < ActionController::Base
+  helper_method :logged_in?
+
+  private
+
+  def logged_in?
+    !!session[:user_id]
+  end
 end
diff --git a/app/controllers/user_sessions_controller.rb b/app/controllers/user_sessions_controller.rb
index 8d71605..816d593 100644
--- a/app/controllers/user_sessions_controller.rb
+++ b/app/controllers/user_sessions_controller.rb
@@ -6,4 +6,9 @@ def create
     session[:user_id] = user.id
     redirect_to new_group_path, notice: 'ログインしました'
   end
+
+  def destroy
+    reset_session
+    redirect_to root_path, notice: 'ログアウトしました'
+  end
 end
diff --git a/app/views/groups/index.html.slim b/app/views/groups/index.html.slim
index 0cb071c..2f2d9e1 100644
--- a/app/views/groups/index.html.slim
+++ b/app/views/groups/index.html.slim
@@ -10,9 +10,12 @@ p.mb-4
   = link_to '2次会グループを作成', new_group_path
 
 .mb-4
-  = button_to 'サインアップ / ログインをして2次会グループを作成', '/auth/github', data: { turbo: false }
-  span.text-xs
-    | GitHubアカウントが必要です
+  - if logged_in?
+    = button_to 'ログアウト', logout_path, method: :delete
+  - else
+    = button_to 'サインアップ / ログインをして2次会グループを作成', '/auth/github', data: { turbo: false }
+    span.text-xs
+      | GitHubアカウントが必要です
 
 p.text-xl.font-bold.mb-4
   | 2次会グループ一覧
diff --git a/config/routes.rb b/config/routes.rb
index a3676cb..d14a46c 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -9,4 +9,5 @@
   # Defines the root path route ("/")
   root "groups#index"
   get "auth/:provider/callback" => "user_sessions#create"
+  delete "/logout" => "user_sessions#destroy"
 end
diff --git a/spec/requests/user_sessions_spec.rb b/spec/requests/user_sessions_spec.rb
index 9e3bce3..00ea616 100644
--- a/spec/requests/user_sessions_spec.rb
+++ b/spec/requests/user_sessions_spec.rb
@@ -48,4 +48,18 @@
       end
     end
   end
+
+  describe 'DELETE /destroy' do
+    it 'removes user id from session' do
+      get '/auth/github/callback'
+      expect(session[:user_id]).to be_present
+      delete '/logout'
+      expect(session[:user_id]).to be_nil
+    end
+
+    it 'redirects to root_path' do
+      delete '/logout'
+      expect(response).to redirect_to(root_path)
+    end
+  end
 end
diff --git a/spec/system/users_spec.rb b/spec/system/users_spec.rb
index f25010d..d9c2212 100644
--- a/spec/system/users_spec.rb
+++ b/spec/system/users_spec.rb
@@ -20,5 +20,22 @@
 
       expect(page).to have_current_path(new_group_path)
     end
+
+    it 'allows users to logout' do
+      visit root_path
+      expect(page).to have_content 'GitHubアカウントが必要です'
+      expect(page).not_to have_content 'ログアウト'
+
+      click_button 'サインアップ / ログインをして2次会グループを作成'
+      expect(page).to have_current_path(new_group_path)
+
+      click_link 'キャンセル'
+      expect(page).to have_current_path(groups_path)
+      expect(page).not_to have_content 'GitHubアカウントが必要です'
+
+      click_button 'ログアウト'
+      expect(page).to have_content 'ログアウトしました'
+      expect(page).to have_content 'GitHubアカウントが必要です'
+    end
   end
 end