diff --git a/api b/api
index 4da3605..3a3bf8b 160000
--- a/api
+++ b/api
@@ -1 +1 @@
-Subproject commit 4da360531810f3a62870d14599a0b87abb767e54
+Subproject commit 3a3bf8b8b366934a543cf031f47b16ee0ee1cb1e
diff --git a/bin/console b/bin/console
index 1bad6ee..6b59ce3 100755
--- a/bin/console
+++ b/bin/console
@@ -3,8 +3,15 @@
 require "bundler/setup"
 require "chatwork"
 require "dotenv"
+require "faraday_curl"
 
 Dotenv.load
 
+logger = Logger.new(STDOUT)
+
+@client = ChatWork::Client.new(api_key: ENV["CHATWORK_API_TOKEN"])
+connection = @client.instance_variable_get(:@conn)
+connection.request(:curl, logger, :debug)
+
 require "pry"
 Pry.start
diff --git a/chatwork.gemspec b/chatwork.gemspec
index 5226589..7225c5f 100644
--- a/chatwork.gemspec
+++ b/chatwork.gemspec
@@ -25,6 +25,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "bundler", "~> 1.3"
   spec.add_development_dependency "coveralls"
   spec.add_development_dependency "dotenv"
+  spec.add_development_dependency "faraday_curl"
   spec.add_development_dependency "onkcop", "0.53.0.0"
   spec.add_development_dependency "pry-byebug"
   spec.add_development_dependency "rake"
diff --git a/lib/chatwork.rb b/lib/chatwork.rb
index e0b5267..bd17cf1 100644
--- a/lib/chatwork.rb
+++ b/lib/chatwork.rb
@@ -1,5 +1,6 @@
 require "chatwork/version"
 require "hashie"
+require "faraday"
 
 module ChatWork
   autoload :BaseClient,         "chatwork/base_client"
diff --git a/lib/chatwork/base_client.rb b/lib/chatwork/base_client.rb
index 3ada4a9..fb6492c 100644
--- a/lib/chatwork/base_client.rb
+++ b/lib/chatwork/base_client.rb
@@ -16,6 +16,7 @@ def initialize(api_base:, api_version: "", header:)
       default_header.merge!(header)
 
       @conn = Faraday.new(api_base, headers: default_header) do |builder|
+        builder.request :multipart
         builder.request :url_encoded
         builder.response :mashify
         builder.response :json
diff --git a/lib/chatwork/client/file_methods.rb b/lib/chatwork/client/file_methods.rb
index 2bc97fb..a768381 100644
--- a/lib/chatwork/client/file_methods.rb
+++ b/lib/chatwork/client/file_methods.rb
@@ -64,4 +64,39 @@ def get_files(room_id:, account_id:, &block)
   def find_file(room_id:, file_id:, create_download_url: nil, &block)
     get("/rooms/#{room_id}/files/#{file_id}", create_download_url: boolean_to_integer(create_download_url), &block)
   end
+
+  # Upload a new file to room
+  #
+  # @see http://developer.chatwork.com/ja/endpoint_rooms.html#POST-rooms-room_id-files
+  # @see http://download.chatwork.com/ChatWork_API_Documentation.pdf
+  #
+  # @param room_id [Integer]
+  # @param file    [Faraday::UploadIO]
+  # @param message [String]
+  #
+  # @yield [response_body, response_header] if block was given, return response body and response header through block arguments
+  # @yieldparam response_body [Hashie::Mash] response body
+  # @yieldparam response_header [Hash<String, String>] response header (e.g. X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset)
+  #
+  # @return [Hashie::Mash]
+  #
+  # @example how to upload a file
+  #   client = ChatWork::Client.new(api_key: "XXX")
+  #   client.create_file(room_id: 11111111, file: Faraday::UploadIO.new("/path/to/file.txt", "text/plain"), message: "Test")
+  #
+  # @example response format
+  #   {
+  #     "file_id": 1234
+  #   }
+  #
+  def create_file(room_id:, file:, message: nil, &block)
+    params = {
+      file: file,
+    }
+    params[:message] = message if message
+
+    post("/rooms/#{room_id}/files", params, &block)
+  end
+
+  alias_method :upload_file, :create_file
 end
diff --git a/lib/chatwork/file.rb b/lib/chatwork/file.rb
index 1a9b0ec..9b8971e 100644
--- a/lib/chatwork/file.rb
+++ b/lib/chatwork/file.rb
@@ -65,5 +65,36 @@ def self.get(room_id:, account_id:, &block)
     def self.find(room_id:, file_id:, create_download_url: nil, &block)
       ChatWork.client.find_file(room_id: room_id, file_id: file_id, create_download_url: create_download_url, &block)
     end
+
+    # Upload a new file to room
+    #
+    # @see http://developer.chatwork.com/ja/endpoint_rooms.html#POST-rooms-room_id-files
+    # @see http://download.chatwork.com/ChatWork_API_Documentation.pdf
+    #
+    # @param room_id [Integer]
+    # @param file    [Faraday::UploadIO]
+    # @param message [String]
+    #
+    # @yield [response_body, response_header] if block was given, return response body and response header through block arguments
+    # @yieldparam response_body [Hashie::Mash] response body
+    # @yieldparam response_header [Hash<String, String>] response header (e.g. X-RateLimit-Limit, X-RateLimit-Remaining, X-RateLimit-Reset)
+    #
+    # @return [Hashie::Mash]
+    #
+    # @example how to upload a file
+    #   ChatWork::File.create(room_id: 11111111, file: Faraday::UploadIO.new("/path/to/file.txt", "text/plain"), message: "Test")
+    #
+    # @example response format
+    #   {
+    #     "file_id": 1234
+    #   }
+    #
+    def self.create(room_id:, file:, message: nil, &block)
+      ChatWork.client.create_file(room_id: room_id, file: file, message: message, &block)
+    end
+
+    class << self
+      alias_method :upload, :create
+    end
   end
 end
diff --git a/spec/data/upload.txt b/spec/data/upload.txt
new file mode 100644
index 0000000..5539005
--- /dev/null
+++ b/spec/data/upload.txt
@@ -0,0 +1 @@
+Hello ChatWork!
diff --git a/spec/lib/chatwork/client/file_methods_spec.rb b/spec/lib/chatwork/client/file_methods_spec.rb
index 124297e..0c6476b 100644
--- a/spec/lib/chatwork/client/file_methods_spec.rb
+++ b/spec/lib/chatwork/client/file_methods_spec.rb
@@ -34,4 +34,18 @@
       it_behaves_like :a_chatwork_api, :get, "/rooms/{room_id}/files/{file_id}"
     end
   end
+
+  describe "#create_file", type: :api do
+    subject { client.create_file(room_id: room_id, file: file, message: message, &block) }
+
+    before do
+      stub_chatwork_request(:post, "/rooms/#{room_id}/files", "/rooms/{room_id}/files")
+    end
+
+    let(:room_id) { 123 }
+    let(:file)    { Faraday::UploadIO.new("#{spec_dir}/data/upload.txt", "text/plain") }
+    let(:message) { "I attached comment to chat." }
+
+    it_behaves_like :a_chatwork_api, :post, "/rooms/{room_id}/files"
+  end
 end
diff --git a/spec/lib/chatwork/file_spec.rb b/spec/lib/chatwork/file_spec.rb
index 0a99654..b147c40 100644
--- a/spec/lib/chatwork/file_spec.rb
+++ b/spec/lib/chatwork/file_spec.rb
@@ -34,4 +34,18 @@
       it_behaves_like :a_chatwork_api, :get, "/rooms/{room_id}/files/{file_id}"
     end
   end
+
+  describe ".create", type: :api do
+    subject { ChatWork::File.create(room_id: room_id, file: file, message: message, &block) }
+
+    before do
+      stub_chatwork_request(:post, "/rooms/#{room_id}/files", "/rooms/{room_id}/files")
+    end
+
+    let(:room_id) { 123 }
+    let(:file)    { Faraday::UploadIO.new("#{spec_dir}/data/upload.txt", "text/plain") }
+    let(:message) { "I attached comment to chat." }
+
+    it_behaves_like :a_chatwork_api, :post, "/rooms/{room_id}/files"
+  end
 end