To provide an audio output circuit that can effectively suppress a noise sound generated when a sound source of a loud speaker is switched over by using a very simple configuration in the case that an audio device and other audio output device share the loud speaker.

An output bias voltage of a SEPP circuit 23a included in a BTL power amplifier IC 23 at a side of an on-vehicle audio unit 22 and an output bias voltage of a power amplifier 26 at a side of a car navigation device 27b are respectively selected to be about a half of an output voltage of a battery 21. A DC component preventing capacitor 27 for the power amplifier 26 is interposed between an output terminal 25b and a ground terminal. Thus, a voltage between output terminals 22a and 25b possibly brought into a connected state via a speaker 24 that is caused by a temporal deviation of a timing of contact switching operation of relay switches 28, 29 is decreased so as to suppress production of a noise sound.