PURPOSE: To attain connection state with inexpensive constitution and rich in expanding for recepion terminal devices by providing an interface device changeing over the input and output direction of a signal between each reception terminal device and a common bus line.

CONSTITUTION: A video disc 3, a personal computer 4, a VTR5 and a television receiver 6 are installed as the reception terminal devices, and a video signal input/output line and an audio signal input/output line of each device are connected to a bus line 11 via interface devices 7∼10. The interface devices 7∼10 are provided to change over the input and output direction of a video signal VID and audio signals AD1, AD2 among the video signal input/output line and the audio signal input/output line of each device and the bus line 11, and this changeover operation is controlled by a control signal from a controller 12.