diff --git a/.travis.yml b/.travis.yml
index 68dd3c9..bc7dd1e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,6 @@
 language: ruby
 rvm:
-  - 2.1.1
+  - 2.1.2
 deploy:
   provider: heroku
   api_key:
diff --git a/Gemfile b/Gemfile
index 827daf8..e35c167 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,9 +1,9 @@
-ruby '2.1.1'
+ruby '2.1.2'
 
 source 'https://rubygems.org'
 source 'https://rails-assets.org'
 
-gem 'rails', '4.1.0'
+gem 'rails', '4.1.1'
 gem 'sass-rails', '~> 4.0.0'
 gem 'uglifier', '>= 1.3.0'
 gem 'coffee-rails', '~> 4.0.0'
@@ -26,14 +26,14 @@ group :development, :test do
   gem 'pry-byebug'
   gem "binding_of_caller"
   gem 'meta_request'
-  gem 'rspec-rails', '~> 3.0.0.beta', github: 'rspec/rspec-rails'
-  gem 'rspec-core', '~> 3.0.0.beta', github: 'rspec/rspec-core'
-  gem 'rspec-expectations', '~> 3.0.0.beta', github: 'rspec/rspec-expectations'
-  gem 'rspec-mocks', '~> 3.0.0.beta', github: 'rspec/rspec-mocks'
-  gem 'rspec-support', '~> 3.0.0.beta', github: 'rspec/rspec-support'
+  gem 'rspec-rails', '~> 3.0.0.rc1'
   gem 'factory_girl_rails', '~> 4.4.1'
 end
 
+group :development do
+  gem 'quiet_assets'
+end
+
 group :test do
   gem 'shoulda-matchers', '~> 2.6.0'
   gem 'capybara'
diff --git a/Gemfile.lock b/Gemfile.lock
index 4e81c56..6971b1b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,71 +1,28 @@
-GIT
-  remote: git://github.com/rspec/rspec-core.git
-  revision: 6b67068d1ae0525d15c02f3a1b00218e5b36b4db
-  specs:
-    rspec-core (3.0.0.beta2)
-      rspec-support (= 3.0.0.beta2)
-
-GIT
-  remote: git://github.com/rspec/rspec-expectations.git
-  revision: 1603a39f45d6683b562ed91a5c766d83e2f3cb20
-  specs:
-    rspec-expectations (3.0.0.beta2)
-      diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (= 3.0.0.beta2)
-
-GIT
-  remote: git://github.com/rspec/rspec-mocks.git
-  revision: d2be1035a098b89d591d4573becae086452baf8c
-  specs:
-    rspec-mocks (3.0.0.beta2)
-      rspec-support (= 3.0.0.beta2)
-
-GIT
-  remote: git://github.com/rspec/rspec-rails.git
-  revision: 3d63b16bc6d8f8cf6d605e1d62e940f8441d0cd7
-  specs:
-    rspec-rails (3.0.0.beta2)
-      actionpack (>= 3.0)
-      activemodel (>= 3.0)
-      activesupport (>= 3.0)
-      railties (>= 3.0)
-      rspec-collection_matchers
-      rspec-core (= 3.0.0.beta2)
-      rspec-expectations (= 3.0.0.beta2)
-      rspec-mocks (= 3.0.0.beta2)
-      rspec-support (= 3.0.0.beta2)
-
-GIT
-  remote: git://github.com/rspec/rspec-support.git
-  revision: 2d12b1e2368054cf9997fa2b2e41329769aa812d
-  specs:
-    rspec-support (3.0.0.beta2)
-
 GEM
   remote: https://rubygems.org/
   remote: https://rails-assets.org/
   specs:
-    actionmailer (4.1.0)
-      actionpack (= 4.1.0)
-      actionview (= 4.1.0)
+    actionmailer (4.1.1)
+      actionpack (= 4.1.1)
+      actionview (= 4.1.1)
       mail (~> 2.5.4)
-    actionpack (4.1.0)
-      actionview (= 4.1.0)
-      activesupport (= 4.1.0)
+    actionpack (4.1.1)
+      actionview (= 4.1.1)
+      activesupport (= 4.1.1)
       rack (~> 1.5.2)
       rack-test (~> 0.6.2)
-    actionview (4.1.0)
-      activesupport (= 4.1.0)
+    actionview (4.1.1)
+      activesupport (= 4.1.1)
       builder (~> 3.1)
       erubis (~> 2.7.0)
-    activemodel (4.1.0)
-      activesupport (= 4.1.0)
+    activemodel (4.1.1)
+      activesupport (= 4.1.1)
       builder (~> 3.1)
-    activerecord (4.1.0)
-      activemodel (= 4.1.0)
-      activesupport (= 4.1.0)
+    activerecord (4.1.1)
+      activemodel (= 4.1.1)
+      activesupport (= 4.1.1)
       arel (~> 5.0.0)
-    activesupport (4.1.0)
+    activesupport (4.1.1)
       i18n (~> 0.6, >= 0.6.9)
       json (~> 1.7, >= 1.7.7)
       minitest (~> 5.1)
@@ -148,8 +105,8 @@ GEM
     method_source (0.8.2)
     mime-types (1.25.1)
     mini_portile (0.5.3)
-    minitest (5.3.3)
-    multi_json (1.9.2)
+    minitest (5.3.4)
+    multi_json (1.10.1)
     newrelic_rpm (3.8.0.218)
     nokogiri (1.6.1)
       mini_portile (~> 0.5.0)
@@ -180,20 +137,22 @@ GEM
     pry-remote (0.1.8)
       pry (~> 0.9)
       slop (~> 3.0)
+    quiet_assets (1.0.2)
+      railties (>= 3.1, < 5.0)
     rack (1.5.2)
     rack-contrib (1.1.0)
       rack (>= 0.9.1)
     rack-test (0.6.2)
       rack (>= 1.0)
-    rails (4.1.0)
-      actionmailer (= 4.1.0)
-      actionpack (= 4.1.0)
-      actionview (= 4.1.0)
-      activemodel (= 4.1.0)
-      activerecord (= 4.1.0)
-      activesupport (= 4.1.0)
+    rails (4.1.1)
+      actionmailer (= 4.1.1)
+      actionpack (= 4.1.1)
+      actionview (= 4.1.1)
+      activemodel (= 4.1.1)
+      activerecord (= 4.1.1)
+      activesupport (= 4.1.1)
       bundler (>= 1.3.0, < 2.0)
-      railties (= 4.1.0)
+      railties (= 4.1.1)
       sprockets-rails (~> 2.0)
     rails-assets-bootstrap (3.1.1)
       rails-assets-jquery (>= 1.9.0)
@@ -203,15 +162,29 @@ GEM
       rails_stdout_logging
     rails_serve_static_assets (0.0.2)
     rails_stdout_logging (0.0.3)
-    railties (4.1.0)
-      actionpack (= 4.1.0)
-      activesupport (= 4.1.0)
+    railties (4.1.1)
+      actionpack (= 4.1.1)
+      activesupport (= 4.1.1)
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
-    rake (10.3.1)
+    rake (10.3.2)
     ref (1.0.5)
-    rspec-collection_matchers (0.0.3)
-      rspec-expectations (>= 2.99.0.beta1)
+    rspec-core (3.0.0.rc1)
+      rspec-support (= 3.0.0.rc1)
+    rspec-expectations (3.0.0.rc1)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (= 3.0.0.rc1)
+    rspec-mocks (3.0.0.rc1)
+      rspec-support (= 3.0.0.rc1)
+    rspec-rails (3.0.0.rc1)
+      actionpack (>= 3.0)
+      activesupport (>= 3.0)
+      railties (>= 3.0)
+      rspec-core (= 3.0.0.rc1)
+      rspec-expectations (= 3.0.0.rc1)
+      rspec-mocks (= 3.0.0.rc1)
+      rspec-support (= 3.0.0.rc1)
+    rspec-support (3.0.0.rc1)
     ruby_parser (3.1.3)
       sexp_processor (~> 4.1)
     sass (3.2.19)
@@ -278,14 +251,11 @@ DEPENDENCIES
   pry
   pry-byebug
   pry-remote
-  rails (= 4.1.0)
+  quiet_assets
+  rails (= 4.1.1)
   rails-assets-bootstrap
   rails_12factor
-  rspec-core (~> 3.0.0.beta)!
-  rspec-expectations (~> 3.0.0.beta)!
-  rspec-mocks (~> 3.0.0.beta)!
-  rspec-rails (~> 3.0.0.beta)!
-  rspec-support (~> 3.0.0.beta)!
+  rspec-rails (~> 3.0.0.rc1)
   sass-rails (~> 4.0.0)
   shoulda-matchers (~> 2.6.0)
   sqlite3
diff --git a/README.md b/README.md
index cc5eeab..e6bb314 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # デザインビギナーズのアイデア帳
 
 [![Build Status](https://travis-ci.org/design-beginners/debeg-idea.svg?branch=master)](https://travis-ci.org/design-beginners/debeg-idea)
+[![Code Climate](https://codeclimate.com/github/design-beginners/debeg-idea.png)](https://codeclimate.com/github/design-beginners/debeg-idea)
 
 ## Setup for development
 
diff --git a/app/assets/javascripts/ideas.js.coffee b/app/assets/javascripts/ideas.js.coffee
index 24f83d1..1b86163 100644
--- a/app/assets/javascripts/ideas.js.coffee
+++ b/app/assets/javascripts/ideas.js.coffee
@@ -1,3 +1,8 @@
 # Place all the behaviors and hooks related to the matching controller here.
 # All this logic will automatically be available in application.js.
 # You can use CoffeeScript in this file: http://coffeescript.org/
+#
+
+$(document).on 'ajax:success', '.js-like', (xhr, data, status) ->
+  location.reload()
+
diff --git a/app/controllers/application_controller.rb b/app/controllers/application_controller.rb
index 63be4c0..b4c7ffc 100644
--- a/app/controllers/application_controller.rb
+++ b/app/controllers/application_controller.rb
@@ -21,7 +21,7 @@ def authenticate
     redirect_to root_path, alert: 'ログインしてください'
   end
 
-  def error404(e)
+  def error404
     render 'error404', status: 404, formats: [:html]
   end
 
diff --git a/app/controllers/likes_controller.rb b/app/controllers/likes_controller.rb
new file mode 100644
index 0000000..161c176
--- /dev/null
+++ b/app/controllers/likes_controller.rb
@@ -0,0 +1,17 @@
+class LikesController < ApplicationController
+  before_action :authenticate
+
+  def create
+    idea = Idea.find(params[:idea_id])
+    comment_id = params[:comment_id]
+
+    likable = if comment_id
+                idea.comments.find(comment_id)
+              else
+                idea
+              end
+    likable.likes.create!(user: current_user)
+
+    head 201
+  end
+end
diff --git a/app/helpers/likes_helper.rb b/app/helpers/likes_helper.rb
new file mode 100644
index 0000000..a78a759
--- /dev/null
+++ b/app/helpers/likes_helper.rb
@@ -0,0 +1,2 @@
+module LikesHelper
+end
diff --git a/app/models/comment.rb b/app/models/comment.rb
index a3d82d4..ffeb03e 100644
--- a/app/models/comment.rb
+++ b/app/models/comment.rb
@@ -1,4 +1,5 @@
 class Comment < ActiveRecord::Base
+  has_many :likes, as: :likable
   belongs_to :idea
   belongs_to :user
 
diff --git a/app/models/idea.rb b/app/models/idea.rb
index bfdf8f2..55b8d4c 100644
--- a/app/models/idea.rb
+++ b/app/models/idea.rb
@@ -1,4 +1,5 @@
 class Idea < ActiveRecord::Base
+  has_many :likes, as: :likable
   has_many :comments
   belongs_to :user
 
diff --git a/app/models/like.rb b/app/models/like.rb
new file mode 100644
index 0000000..7ee0d62
--- /dev/null
+++ b/app/models/like.rb
@@ -0,0 +1,4 @@
+class Like < ActiveRecord::Base
+  belongs_to :user
+  belongs_to :likable, polymorphic: true
+end
diff --git a/app/views/ideas/show.html.haml b/app/views/ideas/show.html.haml
index 60f04d9..f680dcb 100644
--- a/app/views/ideas/show.html.haml
+++ b/app/views/ideas/show.html.haml
@@ -12,6 +12,13 @@
           = comment.body
         - else
           = comment.body
+        .pull-right
+          イイネ！: #{comment.likes.count}
+          - if logged_in? && comment.likes.exists?(user: current_user)
+            = link_to 'イイネ！済み', '#', class: 'btn btn-primary btn-sm disabled'
+          - elsif logged_in?
+            = link_to 'イイネ！', idea_comment_likes_path(@idea, comment), method: :post, remote: true, class: 'btn btn-primary btn-sm js-like'
+
 - if logged_in?
   = form_for [@idea, @comment] do |f|
     - if @comment.errors.any?
diff --git a/app/views/welcome/index.html.haml b/app/views/welcome/index.html.haml
index 2d0fc84..1d00455 100644
--- a/app/views/welcome/index.html.haml
+++ b/app/views/welcome/index.html.haml
@@ -29,3 +29,9 @@
           = idea.title
         - else
           = idea.title
+      .pull-right
+        イイネ！: #{idea.likes.count}
+        - if logged_in? && idea.likes.exists?(user: current_user)
+          = link_to 'イイネ！済み', '#', class: 'btn btn-primary btn-sm disabled'
+        - elsif logged_in?
+          = link_to 'イイネ！', idea_likes_path(idea), method: :post, remote: true, class: 'btn btn-primary btn-sm js-like'
diff --git a/config/routes.rb b/config/routes.rb
index 8c94f3a..7d19ec9 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -4,8 +4,12 @@
   get '/auth/failure' => 'sessions#failure'
   get '/logout' => 'sessions#destroy', as: :logout
 
-  resources :ideas, only: [:show, :create] do
-    resources :comments, only: :create
+  concern :likable do
+    resources :likes, only: :create
+  end
+
+  resources :ideas, concerns: :likable, only: [:show, :create] do
+    resources :comments, concerns: :likable, only: :create
   end
 
   match '*path' => 'application#error404', via: :all
diff --git a/db/migrate/20140507063631_create_likes.rb b/db/migrate/20140507063631_create_likes.rb
new file mode 100644
index 0000000..77d46b7
--- /dev/null
+++ b/db/migrate/20140507063631_create_likes.rb
@@ -0,0 +1,13 @@
+class CreateLikes < ActiveRecord::Migration
+  def change
+    create_table :likes do |t|
+      t.integer :user_id, null: false
+      t.integer :likable_id, null: false
+      t.string  :likable_type, null: false
+      t.timestamps
+    end
+
+    add_index :likes, [:likable_id, :likable_type]
+    add_index :likes, [:user_id, :likable_id, :likable_type], unique: true
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index 58b5f42..f6b3339 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20140427143623) do
+ActiveRecord::Schema.define(version: 20140507063631) do
 
   create_table "comments", force: true do |t|
     t.integer  "idea_id"
@@ -33,6 +33,17 @@
 
   add_index "ideas", ["user_id"], name: "index_ideas_on_user_id"
 
+  create_table "likes", force: true do |t|
+    t.integer  "user_id",      null: false
+    t.integer  "likable_id",   null: false
+    t.string   "likable_type", null: false
+    t.datetime "created_at"
+    t.datetime "updated_at"
+  end
+
+  add_index "likes", ["likable_id", "likable_type"], name: "index_likes_on_likable_id_and_likable_type"
+  add_index "likes", ["user_id", "likable_id", "likable_type"], name: "index_likes_on_user_id_and_likable_id_and_likable_type", unique: true
+
   create_table "users", force: true do |t|
     t.string   "provider",   null: false
     t.string   "uid",        null: false
diff --git a/spec/controllers/likes_controller_spec.rb b/spec/controllers/likes_controller_spec.rb
new file mode 100644
index 0000000..dd39280
--- /dev/null
+++ b/spec/controllers/likes_controller_spec.rb
@@ -0,0 +1,5 @@
+require 'spec_helper'
+
+describe LikesController do
+
+end
diff --git a/spec/features/create_like_to_comment_spec.rb b/spec/features/create_like_to_comment_spec.rb
new file mode 100644
index 0000000..a98a486
--- /dev/null
+++ b/spec/features/create_like_to_comment_spec.rb
@@ -0,0 +1,34 @@
+# -*- coding: utf-8 -*-
+require 'spec_helper'
+
+describe 'よいコメントに"イイネ！"をする' do
+  let(:comment) { create :comment }
+
+  context '未ログイン状態でアイデアページにアクセスしたとき' do
+    before { visit idea_path(comment.idea) }
+
+    it 'イイネ！ボタンが表示されていないこと' do
+      expect(page).to have_no_css '.btn.js-like'
+    end
+  end
+
+  context 'ログイン状態でアイデアページにアクセスしたとき' do
+    before do
+      login
+      visit idea_path(comment.idea)
+    end
+
+    it 'イイネ！ボタンが表示されていること' do
+      expect(find('.btn.js-like')).to have_content 'イイネ！'
+    end
+
+    context 'かつ、イイネ！をクリックしたとき', js: true do
+      before { click_link 'イイネ！' }
+
+      it '"イイネ！" が "イイネ！済み" になり、disabled になっていること' do
+        expect(page).to have_no_css '.btn.js-like'
+        expect(find('.btn.disabled')).to have_content 'イイネ！済み'
+      end
+    end
+  end
+end
diff --git a/spec/features/create_like_to_idea_spec.rb b/spec/features/create_like_to_idea_spec.rb
new file mode 100644
index 0000000..28c34c9
--- /dev/null
+++ b/spec/features/create_like_to_idea_spec.rb
@@ -0,0 +1,34 @@
+# -*- coding: utf-8 -*-
+require 'spec_helper'
+
+describe 'よいアイデアに"イイネ！"をする' do
+  before { create :idea }
+
+  context '未ログイン状態でトップページにアクセスしたとき' do
+    before { visit root_path }
+
+    it 'イイネ！ボタンが表示されていないこと' do
+      expect(page).to have_no_css '.btn.js-like'
+    end
+  end
+
+  context 'ログイン状態でトップページにアクセスしたとき' do
+    before do
+      login
+      visit root_path
+    end
+
+    it 'イイネ！ボタンが表示されていること' do
+      expect(find('.btn.js-like')).to have_content 'イイネ！'
+    end
+
+    context 'かつ、イイネ！をクリックしたとき', js: true do
+      before { click_link 'イイネ！' }
+
+      it '"イイネ！" が "イイネ！済み" になり、disabled になっていること' do
+        expect(page).to have_no_css '.btn.js-like'
+        expect(find('.btn.disabled')).to have_content 'イイネ！済み'
+      end
+    end
+  end
+end
diff --git a/spec/helpers/likes_helper_spec.rb b/spec/helpers/likes_helper_spec.rb
new file mode 100644
index 0000000..483b20c
--- /dev/null
+++ b/spec/helpers/likes_helper_spec.rb
@@ -0,0 +1,15 @@
+require 'spec_helper'
+
+# Specs in this file have access to a helper object that includes
+# the LikesHelper. For example:
+#
+# describe LikesHelper do
+#   describe "string concat" do
+#     it "concats two strings with spaces" do
+#       expect(helper.concat_strings("this","that")).to eq("this that")
+#     end
+#   end
+# end
+describe LikesHelper do
+  pending "add some examples to (or delete) #{__FILE__}"
+end
diff --git a/spec/models/like_spec.rb b/spec/models/like_spec.rb
new file mode 100644
index 0000000..ce06d89
--- /dev/null
+++ b/spec/models/like_spec.rb
@@ -0,0 +1,6 @@
+require 'spec_helper'
+
+describe Like do
+  it { should belong_to :user }
+  it { should belong_to :likable }
+end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index d09b020..b64b929 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -36,7 +36,7 @@
   # If you're not using ActiveRecord, or you'd prefer not to run each of your
   # examples within a transaction, remove the following line or assign false
   # instead of true.
-  config.use_transactional_fixtures = true
+  config.use_transactional_fixtures = false
 
   # Run specs in random order to surface order dependencies. If you find an
   # order dependency and want to debug it, you can fix the order by providing
@@ -65,4 +65,6 @@
   config.after :each do
     DatabaseRewinder.clean
   end
+
+  config.infer_spec_type_from_file_location!
 end