Abstract: Disclosed is an in-vehicle acoustic device capable of accurately controlling the operating state of a portable acoustic device with one button. An in-vehicle audio device (1) serving as the in-vehicle acoustic device is equipped with an antenna (8) which receives a signal indicating the streaming state of a portable audio device (9), and a communication module (2) which transmits operating instruction signals to the portable audio device (9) according to operating signals from an operating unit (5). When the operating unit (5) is operated and the portable audio device (9) is streaming, the communication module (2) transmits a stop instruction signal to stop playback operation by the portable audio device (9), and when the operation unit (5) is operated and the portable audio device (9) is not streaming, the communication module transmits a play instruction signal to start playback operation by the portable audio device (9).