PURPOSE: To amplify an input signal sufficiently to generate a high voltage frequency voltage signal without using high voltage power supply and without constituting a complicated circuit by providing an inductive element inserted between power supply and input electrode of an ultrasonic motor and a switching element to switch on driving frequency of the ultrasonic motor.

CONSTITUTION: When an output of a phase-shifting circuit 2 reaches a high level, a switching element 12 is in a state of conduction, and electric potential of a point A reaches Ov. Accordingly, an electric current is supplied to an inductive element 11 from power supply, and energy accumulated in an input electrode is also discharged. After that, when the output of the phase-shifting circuit 2 reaches a low level, the switching element 12 is in a state of non- conduction, and the electric potential of the point A is increased. While, in order to drive an ultrasonic motor, the electric potential of the point A drops from some point, because the energy is consumed. The output of the phase- shifting circuit 2 reaches a high-level again, and the same operation is repeated.