Abstract: An ultrasonic motor device comprises a vibrating member, a moving member movably disposed on the vibrating member and driven by vibration of the vibrating member, and a pressure regulating member for urging the moving member into pressure contact with the vibrating member. A self-excited vibration circuit has a piezo-electric element having a first surface supporting at least one group of electrodes and a second surface supporting the vibrating member to be vibrationally driven by the piezo-electric element, an amplifying circuit for receiving a voltage generated on the second surface of the piezo-electric element and amplifying the received voltage to a predetermined voltage level, and a boosting circuit for boosting an output voltage of the amplifying circuit and applying the boosted output voltage to the group of electrodes of the piezo-electric element to vibrationally drive the vibrating member.