PURPOSE: To regulate control parameters automatically by regulating setting of control parameters at respective sections based on a speed command, obtained when the motor speed is subjected to step response, or a shift from a stepped speed response waveform.

CONSTITUTION: A parameter regulating section 11 is additionally provided, and the speed waveform is stored in a waveform analyzing section 10 in order to calculate characteristic amounts such as overshoot, setting time or rising time. In the waveform analyzing section 10, the speed waveform is sampled at a sample and hold circuit 10a and stored in a memory 10b and a microprocessor 10c calculates characteristic amounts. Speed control parameters in the speed control loop of a motor 1 are then regulated so that the speed waveform satisfies specification of speed control. The operation is repeated until a judgment is made that the speed control specifications are satisfied within an appropriate allowance thus regulating the speed control parameters correctly.