PURPOSE: To obtain an excellent vibration suppression effect by a method wherein a torque command generating means which generates a torque command supplied to a torque control inverter in accordance with a predetermined speed command and a rotating direction acceleration detected by a rotating direction acceleration detecting means is provided.

CONSTITUTION: As a torque command is obtained by supplying a speed instruction to a torque command generating part 6 and supplied to a torque control inverter 3, an AC voltage for making a motor 4b rotate with a predetermined speed is applied to the motor 4b from the torque control inverter 3. Therefore, a rotary compressor 4a follows the motor 4b to rotate. The rotating direction acceleration of the rotary compressor 4a is detected by a rotating direction acceleration detecting part 5 and a rotating direction acceleration detection signal is fed back to the torque command generating part 6 to compensate the torque command. With this constitution, the generated torque of the motor 4b can be varied in accordance with the variation of a load torque and vibration accompanying the operation of the rotary compressor 4a can be suppressed substantially.