PURPOSE: To completely perform the processing of regenerative relaying and processing of collision for information signals among ≥3 coaxial cables, by transmitting a collision signal to all the transmission lines, at the detection of collision corresponding to some transmission lines.

CONSTITUTION: An information signal is transmitted from a work station connected to a coaxial cable 14A, a carrier detection circuit CSA detects it and contacts SA1, SB2 and SC2 are closed. With a little time delay, when a work station connected to a coaxial cable 14B makes transmission, collision tales place on the cable 14B, and this collision is detected at a detection circuit CDB and fad to a control section CTL. The control section CTL operates a prescribed contact, starts a collision signal generating circuit CSG and transmits the collision signal to cables 14A∼14C via regnerating devices 310A∼310C and prescribed contacts.