PURPOSE: To obtain driving circuit for a composite driving ultrasonic motor which is free of the heat breakdown by constituting a control circuit such that it doubles as a revolutions detecting means, which detects the revolutions of the ultrasonic motor, and a revolutions control means.

CONSTITUTION: When a two-phase rectangular wave is output from an oscillator 30, it becomes the two-phase clock of 50% in duty with comparators 1 and 2, and drives a transformer 32, and a longitudinal oscillating element 18 expands and contacts, and constant power is supplied regardless of the revolutions an ultrasonic motor 10. Moreover, it is output to comparators 3 and 4, too, and drives a transformer 34 and torsional oscillation occurs in a torsional oscillating element 22, and the oscillations are combined, and continuous revolution occurs in a rotor 14. Furthermore, the output from an encoder 36 is input into an F/V converter 38, and the voltage is input into an error amplifier 40 and the comparators 3 and 4, and are compared with set speed voltage, and then, a modulated pulse wave drives the transformer 34, and the fed-back current is input into the torsional oscillating element 22, and the rotational speed is kept at set speed.