diff --git a/app/controllers/comments_controller.rb b/app/controllers/comments_controller.rb
new file mode 100644
index 0000000..bff074e
--- /dev/null
+++ b/app/controllers/comments_controller.rb
@@ -0,0 +1,46 @@
+class CommentsController < ApplicationController
+
+  skip_before_filter :authenticate_user!
+
+  before_action :set_post
+  before_action :set_comment, only: [:show, :update, :destroy]
+
+  def index
+    @comments = Comment.all
+    render json: @comments
+  end
+
+  def show
+    render json: @comment
+  end
+
+  def create
+    @comment = @post.comments.create(comment_params)
+    render json: @comment
+
+  end
+
+  def update
+    @comment.update(comment_params)
+    render json: @comment
+  end
+
+  def destroy
+    @comment.destroy
+    render json: { message: "destoryed" }
+  end
+
+  private
+    def set_post
+      @post = Post.find(params[:post_id])
+    end
+
+    def set_comment
+      @comment = @post.comments.find(params[:id])
+    end
+
+    def comment_params
+      params.require(:comment).permit(:content)
+    end
+
+end
diff --git a/app/controllers/posts_controller.rb b/app/controllers/posts_controller.rb
new file mode 100644
index 0000000..0c53467
--- /dev/null
+++ b/app/controllers/posts_controller.rb
@@ -0,0 +1,40 @@
+class PostsController < ApplicationController
+ 
+  skip_before_filter :authenticate_user!
+
+  before_action :set_post, only: [:show, :update, :destroy]
+
+  def index
+    @posts = Post.all
+    render json: @posts
+  end
+
+  def show
+    render json: @post
+  end
+
+  def create
+    @post = Post.create(post_params)
+    render json: @post
+  end
+
+  def update
+    @post.update(post_params)
+    render json: @post
+  end
+
+  def destroy
+    @post.destroy
+    render json: { message: "destroyed" }
+  end
+
+  private
+    def set_post
+      @post = Post.find(params[:id])
+    end
+
+    def post_params
+      params.require(:post).permit(:title, :content)
+    end
+
+end
diff --git a/config/routes.rb b/config/routes.rb
index c5476d5..3ec0642 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -17,57 +17,63 @@
     end
 
 
-    # You can have the root of your site routed with "root"
-    # root 'welcome#index'
+  concern :commentable do
+    resources :comments, only: [ :index, :show, :create, :update, :destroy ]
+  end
+
+  resources :posts, only: [ :index, :show, :create, :update, :destroy ], concerns: :commentable
+
+  # The priority is based upon order of creation: first created -> highest priority.
+  # See how all your routes lay out with "rake routes".
 
-    # Example of regular route:
-    #   get 'products/:id' => 'catalog#view'
+  # Example of regular route:
+  #   get 'products/:id' => 'catalog#view'
 
-    # Example of named route that can be invoked with purchase_url(id: product.id)
-    #   get 'products/:id/purchase' => 'catalog#purchase', as: :purchase
+  # Example of named route that can be invoked with purchase_url(id: product.id)
+  #   get 'products/:id/purchase' => 'catalog#purchase', as: :purchase
 
-    # Example resource route (maps HTTP verbs to controller actions automatically):
-    #   resources :products
+  # Example resource route (maps HTTP verbs to controller actions automatically):
+  #   resources :products
 
-    # Example resource route with options:
-    #   resources :products do
-    #     member do
-    #       get 'short'
-    #       post 'toggle'
-    #     end
-    #
-    #     collection do
-    #       get 'sold'
-    #     end
-    #   end
+  # Example resource route with options:
+  #   resources :products do
+  #     member do
+  #       get 'short'
+  #       post 'toggle'
+  #     end
+  #
+  #     collection do
+  #       get 'sold'
+  #     end
+  #   end
 
-    # Example resource route with sub-resources:
-    #   resources :products do
-    #     resources :comments, :sales
-    #     resource :seller
-    #   end
+  # Example resource route with sub-resources:
+  #   resources :products do
+  #     resources :comments, :sales
+  #     resource :seller
+  #   end
 
-    # Example resource route with more complex sub-resources:
-    #   resources :products do
-    #     resources :comments
-    #     resources :sales do
-    #       get 'recent', on: :collection
-    #     end
-    #   end
+  # Example resource route with more complex sub-resources:
+  #   resources :products do
+  #     resources :comments
+  #     resources :sales do
+  #       get 'recent', on: :collection
+  #     end
+  #   end
 
-    # Example resource route with concerns:
-    #   concern :toggleable do
-    #     post 'toggle'
-    #   end
-    #   resources :posts, concerns: :toggleable
-    #   resources :photos, concerns: :toggleable
+  # Example resource route with concerns:
+  #   concern :toggleable do
+  #     post 'toggle'
+  #   end
+  #   resources :posts, concerns: :toggleable
+  #   resources :photos, concerns: :toggleable
 
-    # Example resource route within a namespace:
-    #   namespace :admin do
-    #     # Directs /admin/products/* to Admin::ProductsController
-    #     # (app/controllers/admin/products_controller.rb)
-    #     resources :products
-    #   end
+  # Example resource route within a namespace:
+  #   namespace :admin do
+  #     # Directs /admin/products/* to Admin::ProductsController
+  #     # (app/controllers/admin/products_controller.rb)
+  #     resources :products
+  #   end
 
   end
 end
diff --git a/spec/controllers/comments_controller_spec.rb b/spec/controllers/comments_controller_spec.rb
new file mode 100644
index 0000000..1f07689
--- /dev/null
+++ b/spec/controllers/comments_controller_spec.rb
@@ -0,0 +1,129 @@
+require 'spec_helper'
+
+describe CommentsController do
+
+  let(:post_create) { create(:post) }
+  let(:comment) {  create(:comment_to_post, commentable: post_create)  }
+  let(:valid_attributes) { attributes_for(:comment) }
+  let(:invalid_attributes) { attributes_for(:comment, content: nil) }
+
+  describe "GET #index" do
+    it "> 모든 Comment들을 @comments에 할당한다." do
+      comments = [comment, create(:comment_to_post, commentable: post_create)]
+      get :index, post_id: post_create.id
+      expect(assigns(:post)).to eq(post_create)
+      expect(assigns(:comments)).to match_array(comments)
+    end
+  end
+
+  describe "GET #show" do
+    it "> 요청한 Comment로 instance 변수를 할당한다." do
+      get :show, post_id: post_create.id, id: comment
+      expect(assigns(:post)).to eq(post_create)
+      expect(assigns(:comment)).to eq comment
+    end 
+  end
+
+  describe "POST #create" do
+    context "1) params가 유효할 때" do
+      def do_post
+        post :create, post_id: post_create.id, comment: valid_attributes
+      end
+
+      it "> 새로운 Comment를 생성한다." do
+        expect {
+          do_post
+        }.to change(Comment, :count).by(1)
+      end
+
+      it "> Comment instance 변수를 할당한다." do
+        do_post
+        expect(assigns(:comment)).to be_a(Comment)
+        expect(assigns(:comment)).to_not be_new_record
+      end
+    end
+
+    context "2) params가 유효하지 않을 때" do
+      def do_post
+        post :create, post_id: post_create.id, comment: invalid_attributes
+      end
+
+      it "> 새로운 Comment를 생성하지 않는다." do
+        expect{
+          do_post
+        }.to_not change(Comment, :count)
+      end
+
+      it "> 생성하지 못한 Comment로 instance 변수를 할당한다." do
+        do_post
+        expect(assigns(:comment)).to be_a(Comment)
+        expect(assigns(:comment)).to be_new_record
+      end
+    end
+
+  end
+
+  describe 'PATCH #update' do
+    context "1) params가 유효할 때" do
+      def do_patch
+        patch :update, post_id: post_create.id, id: comment,
+          comment: attributes_for(:comment, content: "Answer content changed")
+      end
+
+      it "> 요청한 Comment를 업데이트한다." do
+        do_patch
+        comment.reload
+        expect(comment.content).to eq "Answer content changed"
+      end
+      
+      it "> 요청한 Post와 Comment로 instance 변수를 할당한다." do
+        do_patch
+        comment.reload
+        expect(assigns(:post)).to eq(post_create)
+        expect(assigns(:comment)).to eq comment
+      end
+    end
+
+    context "2) params가 유효하지 않을 때" do
+      def do_patch
+        patch :update, post_id: post_create.id, id: comment, comment: invalid_attributes
+      end
+
+      it "> 요청한 Comment를 업데이트하지 않는다." do
+        do_patch
+        comment.reload
+        expect(comment.content).to eq "abc edf"
+      end
+
+      it "> 요청한 Post와 Comment로 instance 변수를 할당한다." do
+        do_patch
+        comment.reload
+        expect(assigns(:post)).to eq(post_create)
+        expect(assigns(:comment)).to eq comment
+      end
+    end
+  end
+
+  describe 'DELETE #destroy' do
+    before(:each) do
+      @comment = create(:comment, commentable: post_create)
+    end
+
+    def do_delete
+      delete :destroy, post_id: post_create.id, id: @comment
+    end
+
+    it "> 요청한 Comment를 삭제한다." do
+      expect {
+        do_delete
+      }.to change(Comment, :count).by(-1)
+    end
+
+    it "> 요청한 Post와 삭제된 Comment로 instance 변수를 할당한다." do
+      do_delete
+      expect(assigns(:post)).to eq(post_create)
+      expect(assigns(:comment)).to eq(@comment)
+    end
+  end
+
+end
diff --git a/spec/controllers/posts_controller_spec.rb b/spec/controllers/posts_controller_spec.rb
new file mode 100644
index 0000000..61c7e00
--- /dev/null
+++ b/spec/controllers/posts_controller_spec.rb
@@ -0,0 +1,96 @@
+require 'spec_helper'
+
+describe PostsController do
+
+  let(:post_create) { create(:post) }
+  let(:valid_attributes) { attributes_for(:post) }
+  let(:invalid_attributes) { attributes_for(:post, title: nil, content: nil) }
+
+  describe 'GET #index' do
+    it "> 모든 Post로 instance 변수를 할당한다." do
+      posts = [post_create, create(:post)]
+      get :index
+      expect(assigns(:posts)).to match_array(posts)
+    end
+  end
+
+  describe 'GET #show' do
+    it "> 요청한 Post로 instance 변수를 할당한다." do
+      get :show, id: post_create
+      expect(assigns(:post)).to eq post_create
+    end
+  end
+
+  describe 'POST #create' do
+    context "1) params가 유효할 때" do
+      it "> 새로운 Post를 생성한다." do
+        expect {
+          post :create, post: valid_attributes
+        }.to change(Post, :count).by(1)
+      end
+
+      it "> 새로운 Post로 instance 변수를 할당한다." do
+        post :create, post: valid_attributes
+        expect(assigns(:post)).to be_a(Post)
+        expect(assigns(:post)).to_not be_new_record
+      end
+    end
+
+    context "2) params가 유효하지 않을 때" do
+      it "> 새로운 Post를 생성하지 않는다." do
+        expect {
+          post :create, post: invalid_attributes
+        }.to_not change(Post, :count)
+      end
+
+      it "> 새로운 Post를 instance 변수에 할당한다." do
+        post :create, post: invalid_attributes
+        expect(assigns(:post)).to be_a(Post)
+        expect(assigns(:post)).to be_new_record
+      end
+    end
+  end
+
+  describe 'PATCH #update' do
+    context "1) params가 유효할 때" do
+      it "> 요청한 post를 업데이트한다." do
+        patch :update, id: post_create, post: attributes_for(:post, title: "Wonderfulday isn't it?", content: "Yes!!!")
+        post_create.reload
+        expect(post_create.title).to eq("Wonderfulday isn't it?")
+        expect(post_create.content).to eq("Yes!!!")
+      end
+
+      it "> 요청한 post를 instance 변수에 할당한다." do
+        patch :update, id: post_create, post: valid_attributes
+        post_create.reload
+        expect(assigns(:post)).to eq post_create
+      end
+    end
+
+    context "2) params가 유효하지 않을 때" do
+      it "> 요청한 post를 업데이트하지 않는다." do
+        patch :update, id: post_create, post: invalid_attributes
+        post_create.reload
+        expect(post_create.title).to eq("post title")
+        expect(post_create.content).to eq("post content")
+      end
+
+      it "> 요청한 post를 instance 변수에 할당한다." do
+        patch :update, id: post_create, post: invalid_attributes
+        post_create.reload
+        expect(assigns(:post)).to eq post_create
+      end
+    end
+    
+  end
+
+  describe 'DELETE #destroy' do
+    it "> 요청한 post를 삭제한다." do
+      post_create
+      expect {
+        delete :destroy, id: post_create
+      }.to change(Post, :count).by(-1)
+    end
+  end
+
+end
diff --git a/spec/factories/posts.rb b/spec/factories/posts.rb
index 04e71ef..75523de 100644
--- a/spec/factories/posts.rb
+++ b/spec/factories/posts.rb
@@ -19,8 +19,8 @@
 FactoryGirl.define do
   factory :post do
 
-    title "title"
-    content "content"
+    title "post title"
+    content "post content"
  
     # app/models.post.rb에 after_create 선언 해주었습니다.
     # after(:create) do |post|