An ultrasonic motor is driven by ultrasonic waves of which frequency is more than 20kHz. A rotor is moving on a stator which transfers the ultrasonic waves. Piezoelectric devices generate up-and-down movement when AC voltage is applied to. The stator transfers the movement from the bottom to the surface. A traveling-wave to the right on the stator pushes the rotor toward opposite direction, that is, to the left. Because the up-and-down swings at the stator surface make counterclockwise rotation, which results in the rotor’s movement to the left.