To obtain stable high speed vibration, by making the polarity of a cyclic voltage applied to both phase of electric-mechanical energy conversion elements reverse to each other.

A transformer 4 has a primary winding and a secondary winding which are wound in the same direction, but a transformer 13 has a primary winding and a secondary winding wound in reverse direction. Also, the primary windings of both the transformers 4 and 13 are wound in the same direction each other. In this way, the polarity of the secondary side of both the transformers 5 and 14 is reverse to each other, so that a voltage appearing at the ungrounded terminals of the piezoelectric elements 5 and 14 of the oscillatory wave actuator has a distortion in the waveform. When the voltage is applied to the piezoelectric elements of A-phase electrode and B-phase electrode as stated above, even though there is a coupling due to mechanical and electric leakage between A-phase and B-phase, the positive and negative amplitude difference of the synthesized wave of its sum is canceled, and thus the occurrence of abnormal sound during high speed rotation and an increase in rotational irregularity can be suppressed.