An audio apparatus, an audio signal transmission method, and an audio system are provided. The audio signal transmission method includes: wirelessly receiving an audio signal from a first external device; converting the received audio signal into audio signals of multi-channels; and wirelessly transmitting an audio signal of at least one of the multi-channels to at least one of second external devices. Therefore, the audio apparatus wirelessly communicates with a plurality of external devices, and thus a user can connect an audio device to an external device without using wired cables.