A control device for a motor having a stator that generates traveling vibration waves in an elastic member by the excitation of a piezoelectric member, a rotor pressed to contact with the stator and driven by the traveling vibration waves, and a power supply circuit that generates at least one pair of input alternating voltages which are out of phase for exciting the piezoelectric member, and being driven by the vibration waves, comprises a judgment circuit for judging whether the rotor is in an abnormal operating condition, and an amplifying circuit for increasing the voltage magnitude of a pair of alternating voltages from the power supply circuit to a value greater than a predetermined value exceeding the rated voltage of the motor, in response to the fact that the judgment circuit judges that an abnormal operating condition of the motor is in effect.