In the case where (i) audio-video data is unidirectionally transmitted between any device, where (ii) control messages are bidirectionally transmitted between all of the devices, and where (iii) a connection between the devices for transmitting and receiving the audio-video data becomes valid when unidirectional transmission of audio reproduction capability information of the reception device from the data reception device to the data transmission device becomes available, the TV (31) includes the audio reproduction capability information of the AV amplifier (21) to the control message and transmits the control message to the DVD recorder (10) (30M3), and in the case where the DVD recorder (10) and the TV (31) are connected such that the audio-video data is unidirectionally transmitted from the DVD recorder (10) to the TV (31), and where the TV (31) and the AV amplifier (21) are connected such that the audio data is output from the TV (31) to the AV amplifier (21) through another network, the TV (31) does not re-transmit the audio reproduction capability information to the DVD recorder (10) using the unidirectional transmission when transmitting the control message.