To suppress the vibrations at a desired level by controlling the frequency response to the transmission coefficient of a drive transmission system by means of the gain that is calculated based on the original signal vibration level and a desired vibration level.

The frequency response and an FFT (vibration) level are previously measured on the shaft of a DC motor 2, and the compensator coefficient of a velocity compensation arithmetic part 203 is controlled. Thus, a desired FFT level is decided for the revolution of the motor 2. That is, the frequency response is first measured on the shaft of the motor 2 and the gain of the frequency response is decided for the transmission function of a drive transmission system via the FFT measurement. Then the FFT level is measured at a specific frequency where the vibrations are generated to calculate the signal magnification and the FFT level of an original signal. Then the desired FFT level is loaded and compared with the calculated original FFT level. If the latter level is higher than the former one, a compensator is changed.