diff --git a/lib/cli.js b/lib/cli.js
index 4e67e9bf..a6e2d95f 100644
--- a/lib/cli.js
+++ b/lib/cli.js
@@ -68,6 +68,8 @@ program
     , 'adb connect URL pattern'
     , String
     , '${publicIp}:${publicPort}')
+  .option('--mute-master'
+    , 'whether to mute master volume when devices are being used')
   .action(function() {
     var serials = cliutil.allUnknownArgs(arguments)
       , options = cliutil.lastArg(arguments)
@@ -107,7 +109,8 @@ program
         , '--screen-ws-url-pattern', options.screenWsUrlPattern
         , '--connect-url-pattern', options.connectUrlPattern
         , '--heartbeat-interval', options.heartbeatInterval
-        ])
+        ]
+        .concat(options.muteMaster ? ['--mute-master'] : []))
       }
     , endpoints: {
         sub: options.connectSub
@@ -167,6 +170,8 @@ program
     , 'heartbeat interval'
     , Number
     , 10000)
+  .option('--mute-master'
+    , 'whether to mute master volume when devices are being used')
   .action(function(serial, options) {
     if (!options.connectSub) {
       this.missingArgument('--connect-sub')
@@ -204,6 +209,7 @@ program
     , connectUrlPattern: options.connectUrlPattern
     , connectPort: options.connectPort
     , heartbeatInterval: options.heartbeatInterval
+    , muteMaster: options.muteMaster
     })
   })
 
@@ -911,6 +917,8 @@ program
   .option('--user-profile-url <url>'
     , 'URL to external user profile page'
     , String)
+  .option('--mute-master'
+    , 'whether to mute master volume when devices are being used')
   .action(function() {
     var log = logger.createLogger('cli:local')
       , args = arguments
@@ -976,6 +984,7 @@ program
           , '--adb-port', options.adbPort
           ]
           .concat(options.allowRemote ? ['--allow-remote'] : [])
+          .concat(options.muteMaster ? ['--mute-master'] : [])
           .concat(cliutil.allUnknownArgs(args)))
 
         // auth
diff --git a/lib/units/device/index.js b/lib/units/device/index.js
index 461b79c4..fa2a3a29 100644
--- a/lib/units/device/index.js
+++ b/lib/units/device/index.js
@@ -25,6 +25,7 @@ module.exports = function(options) {
         .dependency(require('./plugins/store'))
         .dependency(require('./plugins/clipboard'))
         .dependency(require('./plugins/logcat'))
+        .dependency(require('./plugins/mute'))
         .dependency(require('./plugins/shell'))
         .dependency(require('./plugins/touch'))
         .dependency(require('./plugins/install'))
diff --git a/lib/units/device/plugins/mute.js b/lib/units/device/plugins/mute.js
new file mode 100644
index 00000000..fd23c75b
--- /dev/null
+++ b/lib/units/device/plugins/mute.js
@@ -0,0 +1,30 @@
+var Promise = require('bluebird')
+var syrup = require('stf-syrup')
+
+var logger = require('../../../util/logger')
+
+module.exports = syrup.serial()
+  .dependency(require('./group'))
+  .dependency(require('./service'))
+  .define(function(options, group, service) {
+    var log = logger.createLogger('device:plugins:mute')
+
+    if (options.muteMaster) {
+      log.info('Will mute master volume during use')
+
+      group.on('join', function() {
+        log.info('Muting master volume');
+        service.setMasterMute(true)
+      })
+
+      group.on('leave', function() {
+        log.info('Unmuting master volume');
+        service.setMasterMute(false)
+      })
+    }
+    else {
+      log.info('Will not mute master volume during use')
+    }
+
+    return Promise.resolve()
+  })
diff --git a/lib/units/device/plugins/service.js b/lib/units/device/plugins/service.js
index e61442be..5f8ce68f 100644
--- a/lib/units/device/plugins/service.js
+++ b/lib/units/device/plugins/service.js
@@ -671,6 +671,20 @@ module.exports = syrup.serial()
       return Promise.resolve(true)
     }
 
+    plugin.setMasterMute = function(mode) {
+      return runServiceCommand(
+          apk.wire.MessageType.SET_MASTER_MUTE
+        , new apk.wire.SetMasterMuteRequest(mode)
+        )
+        .timeout(10000)
+        .then(function(data) {
+          var response = apk.wire.SetMasterMuteResponse.decode(data)
+          if (!response.success) {
+            throw new Error('Unable to set master mute')
+          }
+        })
+    }
+
     function runServiceCommand(type, cmd) {
       var resolver = Promise.defer()
       var id = Math.floor(Math.random() * 0xFFFFFF)
diff --git a/lib/units/device/resources/service.js b/lib/units/device/resources/service.js
index 29b2210e..09d89a50 100644
--- a/lib/units/device/resources/service.js
+++ b/lib/units/device/resources/service.js
@@ -17,7 +17,7 @@ module.exports = syrup.serial()
       pathutil.vendor('STFService/wire.proto'))
 
     var resource = {
-      requiredVersion: '1.0.0'
+      requiredVersion: '1.0.1'
     , pkg: 'jp.co.cyberagent.stf'
     , main: 'jp.co.cyberagent.stf.Agent'
     , apk: pathutil.vendor('STFService/STFService.apk')
diff --git a/vendor/STFService/STFService.apk b/vendor/STFService/STFService.apk
index 2477c0a5..322bf510 100644
Binary files a/vendor/STFService/STFService.apk and b/vendor/STFService/STFService.apk differ
diff --git a/vendor/STFService/wire.proto b/vendor/STFService/wire.proto
index 44b07565..e38b9ac3 100644
--- a/vendor/STFService/wire.proto
+++ b/vendor/STFService/wire.proto
@@ -24,6 +24,7 @@ enum MessageType {
     SET_ROTATION = 12;
     SET_WAKE_LOCK = 11;
     SET_WIFI_ENABLED = 22;
+    SET_MASTER_MUTE = 28;
     EVENT_AIRPLANE_MODE = 13;
     EVENT_BATTERY = 14;
     EVENT_CONNECTIVITY = 15;
@@ -251,6 +252,14 @@ message GetSdStatusResponse {
     required bool mounted = 2;
 }
 
+message SetMasterMuteRequest {
+    required bool enabled = 1;
+}
+
+message SetMasterMuteResponse {
+    required bool success = 1;
+}
+
 // Agent
 
 enum KeyEvent {