diff --git a/lib/fluent/command/fluentd.rb b/lib/fluent/command/fluentd.rb
index 1c37b10e41..ed1ad22123 100644
--- a/lib/fluent/command/fluentd.rb
+++ b/lib/fluent/command/fluentd.rb
@@ -81,6 +81,11 @@
   opts[:chgroup] = s
 }
 
+opts[:chumask] = 0
+op.on('--umask UMASK', "change umask") {|s|
+  opts[:chumask] = s
+}
+
 op.on('-o', '--log PATH', "log file path") {|s|
   opts[:log_path] = s
 }
diff --git a/lib/fluent/supervisor.rb b/lib/fluent/supervisor.rb
index c03cde3925..819877e3a4 100644
--- a/lib/fluent/supervisor.rb
+++ b/lib/fluent/supervisor.rb
@@ -397,6 +397,7 @@ def self.load_config(path, params = {})
       log_path = params['log_path']
       chuser = params['chuser']
       chgroup = params['chgroup']
+      chumask = params['chumask']
       log_rotate_age = params['log_rotate_age']
       log_rotate_size = params['log_rotate_size']
 
@@ -436,7 +437,7 @@ def self.load_config(path, params = {})
         logger_initializer: logger_initializer,
         chuser: chuser,
         chgroup: chgroup,
-        chumask: 0,
+        chumask: chumask,
         suppress_repeated_stacktrace: suppress_repeated_stacktrace,
         ignore_repeated_log_interval: ignore_repeated_log_interval,
         ignore_same_log_interval: ignore_same_log_interval,
@@ -603,6 +604,7 @@ def initialize(opt)
       @plugin_dirs = opt[:plugin_dirs]
       @chgroup = opt[:chgroup]
       @chuser = opt[:chuser]
+      @chumask = opt[:chumask]
 
       @log_rotate_age = opt[:log_rotate_age]
       @log_rotate_size = opt[:log_rotate_size]
@@ -709,7 +711,7 @@ def run_worker
         create_socket_manager if @standalone_worker
         if @standalone_worker
           ServerEngine::Privilege.change(@chuser, @chgroup)
-          File.umask(0)
+          File.umask(@chumask.to_i(8))
         end
         MessagePackFactory.init(enable_time_support: @system_config.enable_msgpack_time_support)
         Fluent::Engine.init(@system_config)