PURPOSE: To increase the rising ratio of a receiving wave and to reduce effect due to disturbance, by converting a drive wave form to positive and negative bipolar pulses.

CONSTITUTION: A control circuit 2 outputs the control pulse of a preset pulse width and the number of pulses in matching relation to transmission timing sent at constant intervals and a drive circuit 3 connects an N-channel electric field effect transistor 3a and a P-channel electric field effect transistor 3b comprementarily to constitute a comprementary circuit, and the N-channel electric field effect transistor 3a and the P-channel electric field effect transistor 3b are alternately subjected to ON-and-OFF operation corresponding to the rising and falling of the above mentioned control pulse not only to respectively form a plus pulse and a minus pulse but also to synthesize both pulses to output the same. Therefore, a drive wave form consisting of pulses having positive and negative bipolar amplitudes is outputted in matching relation to transmitting timing of a constant interval.