PURPOSE: To reduce deterioration in a signal waveform on a bus by providing a branch line whose characteristic impedance is almost equal to that of a bus and comprising two pair constitution by being folded after being connected to transmission equipment at termination,

CONSTITUTION: The branch line 12 whose characteristic impedance is almost equal to that of the bus 11 is folded at the inside of the transmission equipment 13, and a transceiver in the transmission equipment 13 is connected to the branch line 12 with a short distance. A switch in a switching device 14 is connected to the switch 2 side of the switch when the branch line 12 is connected, which enables transmission/reception by the transmission equipment 13 to be performed, however, at this time, the path of the bus is formed as A-B-C, that is identical with the direct connection of the transmission equipment 13 to the bus 11. In such a way, influence due to the capacitance of the branch line can be eliminated, and the reflection of a signal on the bus can be reduced, therefore, the deterioration in the signal waveform can be reduced.