diff --git a/lib/fluent/plugin/buf_file.rb b/lib/fluent/plugin/buf_file.rb
index 04fc24394e..98f9e850d8 100644
--- a/lib/fluent/plugin/buf_file.rb
+++ b/lib/fluent/plugin/buf_file.rb
@@ -34,6 +34,8 @@ class FileBuffer < Fluent::Plugin::Buffer
 
       desc 'The path where buffer chunks are stored.'
       config_param :path, :string, default: nil
+      desc 'The suffix of buffer chunks'
+      config_param :path_suffix, :string, default: '.log'
 
       config_set_default :chunk_limit_size, DEFAULT_CHUNK_LIMIT_SIZE
       config_set_default :total_limit_size, DEFAULT_TOTAL_LIMIT_SIZE
@@ -78,12 +80,12 @@ def configure(conf)
 
         if specified_directory_exists || unexisting_path_for_directory # directory
           if using_plugin_root_dir || !multi_workers_configured
-            @path = File.join(@path, 'buffer.*.log')
+            @path = File.join(@path, "buffer.*#{@path_suffix}")
           else
-            @path = File.join(@path, "worker#{fluentd_worker_id}", 'buffer.*.log')
+            @path = File.join(@path, "worker#{fluentd_worker_id}", "buffer.*#{@path_suffix}")
             if fluentd_worker_id == 0
               # worker 0 always checks unflushed buffer chunks to be resumed (might be created while non-multi-worker configuration)
-              @additional_resume_path = File.join(File.expand_path("../../", @path), 'buffer.*.log')
+              @additional_resume_path = File.join(File.expand_path("../../", @path), "buffer.*#{@path_suffix}")
             end
           end
           @multi_workers_available = true
@@ -91,10 +93,10 @@ def configure(conf)
           if File.basename(@path).include?('.*.')
             # valid file path
           elsif File.basename(@path).end_with?('.*')
-            @path = @path + '.log'
+            @path = @path + @path_suffix
           else
             # existing file will be ignored
-            @path = @path + '.*.log'
+            @path = @path + ".*#{@path_suffix}"
           end
           @multi_workers_available = false
         end
diff --git a/test/plugin/test_buf_file.rb b/test/plugin/test_buf_file.rb
index 958c930685..4a341e8143 100644
--- a/test/plugin/test_buf_file.rb
+++ b/test/plugin/test_buf_file.rb
@@ -57,20 +57,30 @@ def write_metadata(path, chunk_id, metadata, size, ctime, mtime)
       assert_equal File.join(@dir, 'buffer.*.file'), p.path
     end
 
-    test 'existing directory will be used with additional default file name' do
+    data('default' => [nil, 'log'],
+         'conf' => ['.buf', 'buf'])
+    test 'existing directory will be used with additional default file name' do |params|
+      conf, suffix = params
       d = FluentPluginFileBufferTest::DummyOutputPlugin.new
       p = Fluent::Plugin::FileBuffer.new
       p.owner = d
-      p.configure(config_element('buffer', '', {'path' => @dir}))
-      assert_equal File.join(@dir, 'buffer.*.log'), p.path
+      c = {'path' => @dir}
+      c['path_suffix'] = conf if conf
+      p.configure(config_element('buffer', '', c))
+      assert_equal File.join(@dir, "buffer.*.#{suffix}"), p.path
     end
 
-    test 'unexisting path without * handled as directory' do
+    data('default' => [nil, 'log'],
+         'conf' => ['.buf', 'buf'])
+    test 'unexisting path without * handled as directory' do |params|
+      conf, suffix = params
       d = FluentPluginFileBufferTest::DummyOutputPlugin.new
       p = Fluent::Plugin::FileBuffer.new
       p.owner = d
-      p.configure(config_element('buffer', '', {'path' => File.join(@dir, 'buffer')}))
-      assert_equal File.join(@dir, 'buffer', 'buffer.*.log'), p.path
+      c = {'path' => File.join(@dir, 'buffer')}
+      c['path_suffix'] = conf if conf
+      p.configure(config_element('buffer', '', c))
+      assert_equal File.join(@dir, 'buffer', "buffer.*.#{suffix}"), p.path
     end
   end
 
@@ -312,10 +322,6 @@ def write_metadata(path, chunk_id, metadata, size, ctime, mtime)
       @d = FluentPluginFileBufferTest::DummyOutputPlugin.new
       @p = Fluent::Plugin::FileBuffer.new
       @p.owner = @d
-      Fluent::SystemConfig.overwrite_system_config('root_dir' => @root_dir) do
-        @d.configure(config_element('ROOT', '', {'@id' => 'dummy_output_with_buf'}))
-        @p.configure(config_element('buffer', ''))
-      end
     end
 
     teardown do
@@ -329,8 +335,18 @@ def write_metadata(path, chunk_id, metadata, size, ctime, mtime)
       end
     end
 
-    test '#start creates directory for buffer chunks' do
-      expected_buffer_path = File.join(@root_dir, 'worker0', 'dummy_output_with_buf', 'buffer', 'buffer.*.log')
+    data('default' => [nil, 'log'],
+         'conf' => ['.buf', 'buf'])
+    test '#start creates directory for buffer chunks' do |params|
+      conf, suffix = params
+      c = {}
+      c['path_suffix'] = conf if conf
+      Fluent::SystemConfig.overwrite_system_config('root_dir' => @root_dir) do
+        @d.configure(config_element('ROOT', '', {'@id' => 'dummy_output_with_buf'}))
+        @p.configure(config_element('buffer', '', c))
+      end
+
+      expected_buffer_path = File.join(@root_dir, 'worker0', 'dummy_output_with_buf', 'buffer', "buffer.*.#{suffix}")
       expected_buffer_dir = File.dirname(expected_buffer_path)
       assert_equal expected_buffer_path, @p.path
       assert_false Dir.exist?(expected_buffer_dir)