To provide an acoustic device that can prevent wasteful current consumptions occurring in its main body and the rise of its internal temperature and, at the same time, can generate sounds of high sound qualities when an external amplifier is connected to the device.

This acoustic device has a built-in amplifier 12 provided in its main body 10 and outputs audio signals by amplifying the signals, a connector 17 which connects the external amplifier 20 used for amplifying the audio signals to the main body 10, and an external amplifier detecting circuit 14 which detects the connected state of the amplifier 20. This device also has a microcomputer 13 which stops the action of the amplifier 12 when it is detected that the amplifier 20 is connected to the main body 10.