diff --git a/lib/fluent/plugin/buf_file.rb b/lib/fluent/plugin/buf_file.rb
index 84a73921ca..4725f5c9fe 100644
--- a/lib/fluent/plugin/buf_file.rb
+++ b/lib/fluent/plugin/buf_file.rb
@@ -39,8 +39,8 @@ class FileBuffer < Fluent::Plugin::Buffer
       config_set_default :chunk_limit_size, DEFAULT_CHUNK_LIMIT_SIZE
       config_set_default :total_limit_size, DEFAULT_TOTAL_LIMIT_SIZE
 
-      config_param :file_permission, :string, default: nil # '0644'
-      config_param :dir_permission,  :string, default: nil # '0755'
+      config_param :file_permission, :string, default: nil # '0644' (Fluent::DEFAULT_FILE_PERMISSION)
+      config_param :dir_permission,  :string, default: nil # '0755' (Fluent::DEFAULT_DIR_PERMISSION)
 
       def initialize
         super
diff --git a/lib/fluent/plugin/output.rb b/lib/fluent/plugin/output.rb
index 354c6649f3..34e31ec878 100644
--- a/lib/fluent/plugin/output.rb
+++ b/lib/fluent/plugin/output.rb
@@ -14,6 +14,7 @@
 #    limitations under the License.
 #
 
+require 'fluent/env'
 require 'fluent/error'
 require 'fluent/plugin/base'
 require 'fluent/plugin/buffer'
@@ -1248,8 +1249,8 @@ def backup_chunk(chunk, using_secondary, delayed_commit)
           backup_dir = File.dirname(backup_file)
 
           log.warn "bad chunk is moved to #{backup_file}"
-          FileUtils.mkdir_p(backup_dir, mode: system_config.dir_permission || 0755) unless Dir.exist?(backup_dir)
-          File.open(backup_file, 'ab', system_config.file_permission || 0644) { |f|
+          FileUtils.mkdir_p(backup_dir, mode: system_config.dir_permission || Fluent::DEFAULT_DIR_PERMISSION) unless Dir.exist?(backup_dir)
+          File.open(backup_file, 'ab', system_config.file_permission || Fluent::DEFAULT_FILE_PERMISSION) { |f|
             chunk.write_to(f)
           }
         end
diff --git a/lib/fluent/plugin/storage_local.rb b/lib/fluent/plugin/storage_local.rb
index d17022fe6b..b9e159f671 100644
--- a/lib/fluent/plugin/storage_local.rb
+++ b/lib/fluent/plugin/storage_local.rb
@@ -14,6 +14,7 @@
 #    limitations under the License.
 #
 
+require 'fluent/env'
 require 'fluent/plugin'
 require 'fluent/plugin/storage'
 
@@ -25,14 +26,11 @@ module Plugin
     class LocalStorage < Storage
       Fluent::Plugin.register_storage('local', self)
 
-      DEFAULT_DIR_MODE = 0755
-      DEFAULT_FILE_MODE = 0644
-
       config_param :path, :string, default: nil
-      config_param :mode, default: DEFAULT_FILE_MODE do |v|
+      config_param :mode, default: Fluent::DEFAULT_FILE_PERMISSION do |v|
         v.to_i(8)
       end
-      config_param :dir_mode, default: DEFAULT_DIR_MODE do |v|
+      config_param :dir_mode, default: Fluent::DEFAULT_DIR_PERMISSION do |v|
         v.to_i(8)
       end
       config_param :pretty_print, :bool, default: false
diff --git a/lib/fluent/plugin_id.rb b/lib/fluent/plugin_id.rb
index 7477327024..87b1bc7ff1 100644
--- a/lib/fluent/plugin_id.rb
+++ b/lib/fluent/plugin_id.rb
@@ -15,6 +15,7 @@
 #
 
 require 'set'
+require 'fluent/env'
 require 'fluent/variable_store'
 
 module Fluent
@@ -76,7 +77,7 @@ def plugin_root_dir
 
       # Fluent::Plugin::Base#fluentd_worker_id
       dir = File.join(system_config.root_dir, "worker#{fluentd_worker_id}", plugin_id)
-      FileUtils.mkdir_p(dir, mode: system_config.dir_permission || 0755) unless Dir.exist?(dir)
+      FileUtils.mkdir_p(dir, mode: system_config.dir_permission || Fluent::DEFAULT_DIR_PERMISSION) unless Dir.exist?(dir)
       @_plugin_root_dir = dir.freeze
       dir
     end
diff --git a/lib/fluent/supervisor.rb b/lib/fluent/supervisor.rb
index 59ef6093ed..c03cde3925 100644
--- a/lib/fluent/supervisor.rb
+++ b/lib/fluent/supervisor.rb
@@ -544,7 +544,7 @@ def apply_options(format: nil, time_format: nil, log_dir_perm: nil, ignore_repea
         $log.ignore_same_log_interval = ignore_same_log_interval if ignore_same_log_interval
 
         if @path && log_dir_perm
-          File.chmod(log_dir_perm || 0755, File.dirname(@path))
+          File.chmod(log_dir_perm || Fluent::DEFAULT_DIR_PERMISSION, File.dirname(@path))
         end
       end
 
@@ -651,7 +651,7 @@ def run_supervisor(dry_run: false)
           end
         else
           begin
-            FileUtils.mkdir_p(root_dir, mode: @system_config.dir_permission || 0755)
+            FileUtils.mkdir_p(root_dir, mode: @system_config.dir_permission || Fluent::DEFAULT_DIR_PERMISSION)
           rescue => e
             raise Fluent::InvalidRootDirectory, "failed to create root directory:#{root_dir}, #{e.inspect}"
           end