diff --git a/lib/fluent/plugin/in_sql.rb b/lib/fluent/plugin/in_sql.rb
index 426aab1..5dc040f 100644
--- a/lib/fluent/plugin/in_sql.rb
+++ b/lib/fluent/plugin/in_sql.rb
@@ -282,7 +282,7 @@ def initialize(path)
         require 'yaml'
 
         @path = path
-        if File.exists?(@path)
+        if File.exist?(@path)
           @data = YAML.load_file(@path)
           if @data == false || @data == []
             # this happens if an users created an empty file accidentally
diff --git a/test/plugin/test_in_sql_with_state_file.rb b/test/plugin/test_in_sql_with_state_file.rb
new file mode 100644
index 0000000..a38879e
--- /dev/null
+++ b/test/plugin/test_in_sql_with_state_file.rb
@@ -0,0 +1,96 @@
+require "helper"
+require "fluent/test/driver/input"
+
+class SqlInputStateFileTest < Test::Unit::TestCase
+  def setup
+    Fluent::Test.setup
+  end
+
+  def teardown
+  end
+
+  CONFIG = %[
+    adapter postgresql
+    host localhost
+    port 5432
+    database fluentd_test
+
+    username fluentd
+    password fluentd
+
+    state_file /tmp/sql_state
+
+    schema_search_path public
+
+    tag_prefix db
+
+    <table>
+      table messages
+      tag logs
+      update_column updated_at
+      time_column updated_at
+    </table>
+  ]
+
+  def create_driver(conf = CONFIG)
+    Fluent::Test::Driver::Input.new(Fluent::Plugin::SQLInput).configure(conf)
+  end
+
+  def test_configure
+    d = create_driver
+    expected = {
+      host: "localhost",
+      port: 5432,
+      adapter: "postgresql",
+      database: "fluentd_test",
+      username: "fluentd",
+      password: "fluentd",
+      schema_search_path: "public",
+      tag_prefix: "db"
+    }
+    actual = {
+      host: d.instance.host,
+      port: d.instance.port,
+      adapter: d.instance.adapter,
+      database: d.instance.database,
+      username: d.instance.username,
+      password: d.instance.password,
+      schema_search_path: d.instance.schema_search_path,
+      tag_prefix: d.instance.tag_prefix
+    }
+    assert_equal(expected, actual)
+    tables = d.instance.instance_variable_get(:@tables)
+    assert_equal(1, tables.size)
+    messages = tables.first
+    assert_equal("messages", messages.table)
+    assert_equal("logs", messages.tag)
+  end
+
+  def test_message
+    d = create_driver(CONFIG + "select_interval 1")
+    Message.create!(message: "message 1")
+    Message.create!(message: "message 2")
+    Message.create!(message: "message 3")
+
+    d.end_if do
+      d.record_count >= 3
+    end
+    d.run
+
+    assert_equal("db.logs", d.events[0][0])
+    expected = [
+      [d.events[0][1], "message 1"],
+      [d.events[1][1], "message 2"],
+      [d.events[2][1], "message 3"],
+    ]
+    actual = [
+      [Fluent::EventTime.parse(d.events[0][2]["updated_at"]), d.events[0][2]["message"]],
+      [Fluent::EventTime.parse(d.events[1][2]["updated_at"]), d.events[1][2]["message"]],
+      [Fluent::EventTime.parse(d.events[2][2]["updated_at"]), d.events[2][2]["message"]],
+    ]
+    assert_equal(expected, actual)
+  end
+
+  class Message < ActiveRecord::Base
+  end
+end