PURPOSE: To start and stop a vibrating mirror smoothly by detecting a timing of a triangle wave for driving so as to select the switching timing of a drive switch.

CONSTITUTION: A trailing point of a switch timing generating circuit 21 is detected when an output of a rectangular wave generator 5 is positive to synchronize a leading waveform of the triangle wave at zero cross point and a switch 2 is applied depending on the simultaneous condition at application of a vibrating mirror 1. In stopping the vibrating mirror 1, the trailing point of the switch timing generating circuit 21 is detected when the waveform of the generator 5 is negative and the switch 2 is shut off with the simultaneous condition. As a result, since the vibrating mirror is started from a zero value of the triangle wave, the mirror is started smoothly from the stop position.