An ultrasonic motor in which driving signals of two phases are applied to a vibrator having a driving member in contact with a driven member to simultaneously generate a longitudinal vibration and a flexural vibration, thereby generating an elliptic vibration in the vibrator, and the driving member frictionally drives the driven member upon obtaining a driving force from the elliptic vibration, is configured as follows. Namely, the ultrasonic motor includes a driving phase difference switching unit which switches a driving phase difference serving as a phase difference between the driving signals of the two phases, and changes a switching cycle of the driving phase difference.