PURPOSE: To prevent intermittent noise by inputting one and same signal from different terminals so as to differentiate the noise generating timing generated at connection of terminals thereby eliminating noise.

CONSTITUTION: Signals 28, 31 include intermittent noise generated at connection of signal transmission terminals 15, 16 and signal reception terminals 23, 24. Thus, a power input terminal 17 and a ground input terminal 18 are connected to signal reception section 12 earlier than the other terminals. Thus, intermittent noise caused in the signals 28, 31 is independent of the connection of the power supply and ground and depends only on the connection of the terminals 15 and 23 and one connection of the terminals 16 and 24. Moreover, since the connecting position between the terminals 15, 23 and the terminals 16, 24 is parted, the generating timings of intermittent noise are differentiated. The signals 28, 31 are inputted to a coincidence detection circuit 41 and a signal from which noise is eliminated is outputted from a selection circuit 42. Thus, intermittent noise is easily and effectively prevented.