To reduce noise by limiting a current peak value to a predetermined value or less and by smoothing the waveforms of drive currents during the current limitation, switching control means (30) according to the present invention turns ON all of one-side drive transistors selected from the high-side drive transistors (21, 22 and 23) and the low-side drive transistors (25, 26 and 27) of power supply means (20) for a predetermined period, and turns OFF all of the other-side drive transistors for a predetermined period in response to a current control signal for the current peak value to a predetermined value or less.