An audio device 100 which replays audio on the basis of an external audio signal PAS outputted from a portable audio device (500) includes: a power supply unit 170, that is a power supply element which supplies power at a predetermined voltage to the portable audio device 500; a control unit 110, that is a control element which, along with notifying to the portable audio device 500 function setting information FRP that is operability information specifying whether or not inherent actuation input is possible using an inherent actuation input element provided to the portable audio device, also controls the details notified; and speakers 130L and 130R, that are audio replay element for replaying audio on the basis of the external audio signal PAS. As a result, an audio device 100 is implemented which can enhance the convenience to the user, in cooperation with the portable audio device 500.