diff --git a/lib/droid/monitor.rb b/lib/droid/monitor.rb
index 641f471..4e02957 100644
--- a/lib/droid/monitor.rb
+++ b/lib/droid/monitor.rb
@@ -1,4 +1,6 @@
 require_relative "monitor/version"
+require_relative "monitor/common/timer"
+require_relative "monitor/executor/executor"
 
 require "Open3"
 
@@ -8,8 +10,8 @@ class Adb
       attr_accessor :package, :device_serial, :api_level
 
       def initialize(opts = {})
-        fail "opts must be a hash" unless opts.is_a? Hash
-        fail "Package name is required." unless opts[:package]
+        raise "opts must be a hash" unless opts.is_a? Hash
+        raise "Package name is required." unless opts[:package]
         @package = opts[:package]
         @device_serial = opts[:device_serial] || ""
         @api_level = device_sdk_version
@@ -64,7 +66,7 @@ def dump_gfxinfo
       private
 
       def adb
-        fail "ANDROID_HOME is not set" unless ENV["ANDROID_HOME"]
+        raise "ANDROID_HOME is not set" unless ENV["ANDROID_HOME"]
         "#{ENV["ANDROID_HOME"]}/platform-tools/adb"
       end
 
diff --git a/lib/droid/monitor/common/timer.rb b/lib/droid/monitor/common/timer.rb
new file mode 100644
index 0000000..250624b
--- /dev/null
+++ b/lib/droid/monitor/common/timer.rb
@@ -0,0 +1,52 @@
+module Droid
+  module Monitor
+    module Timer
+      class Executor
+        attr_reader :interval
+
+        # @param [int] interval Interval to wait
+        def initialize(interval)
+          @interval = interval
+        end
+
+        # @param [Block] &block Yield the block after sleep @interval
+        # @return [Symbol] :finished
+        def execute
+          sleep interval
+          yield
+
+          :finished
+        end
+
+        # Loop `execute` until stopping its process
+        # @param [Block] &block Yield the block after sleep @interval
+        # @return [Symbol] :finished
+        def execute_loop(&block)
+          loop { execute(&block) }
+        end
+
+        # Start
+        #     t = timer.execute_loop_thread { puts "#{Time.now}" }
+        # Stop
+        #     timer.kill_thread t
+        #
+        # Loop `execute` until stopping its process on the other thread
+        # @param [Block] &block Yield the block after sleep @interval
+        # @return [Symbol] :finished
+        def execute_loop_thread(&block)
+          Thread.new { loop { execute(&block) } }
+        end
+
+        # @param [Thread] thread Kill the thread
+        def kill_thread(thread)
+          Thread.kill thread
+        end
+
+        # @return [Array[Thread]] Return a list running thread on the process
+        def thread_list
+          Thread.list
+        end
+      end
+    end
+  end
+end
diff --git a/lib/droid/monitor/executor/executor.rb b/lib/droid/monitor/executor/executor.rb
new file mode 100644
index 0000000..3ddb332
--- /dev/null
+++ b/lib/droid/monitor/executor/executor.rb
@@ -0,0 +1,19 @@
+module Droid
+  module Monitor
+    class Executor
+      class Base
+        def execute(_timer)
+          raise NotImplementedError
+        end
+
+        def save
+          raise NotImplementedError
+        end
+
+        def kill
+          raise NotImplementedError
+        end
+      end
+    end
+  end
+end
diff --git a/test/monitor/timer_test.rb b/test/monitor/timer_test.rb
new file mode 100644
index 0000000..d8bb3de
--- /dev/null
+++ b/test/monitor/timer_test.rb
@@ -0,0 +1,24 @@
+require 'test/unit'
+
+require './lib/droid/monitor/common/timer'
+
+module Droid
+  module Monitor
+    class TimerTest < Test::Unit::TestCase
+      def test_timer
+        timer = Timer::Executor.new(0.1)
+        assert_equal(0.1, timer.interval)
+
+        thread_size = Thread.list.size
+        thread = timer.execute_loop_thread { 1 }
+        assert_equal(thread_size + 1, Thread.list.size)
+        assert_equal('run', thread.status)
+
+        timer.kill_thread thread
+        sleep 0.1
+        assert_equal(false, thread.status)
+        assert_equal(thread_size, Thread.list.size)
+      end
+    end
+  end
+end