is understood that only the disturbance response is improved with substantially no change in the command value response the speed decrease upon the disturbance response is reduced to 70 and the response time until the instant at which the speed recovers is shortened to 30 in addition the ratio of the command value response time and the disturbance response time is approximately 1 and advantages derived from its improvement is extremely great another advantage of the present invention is that the command value response change with respect to variations in the force of inertia of the load can be reduced for example when the inertia is increased greater torque is required to accelerate however the response change can be suppressed similarly to the case where the load torque is applied to this increment of the load further this means that even when the transfer function of the simulated transfer function block which is required for the present invention differs from the actual value to some extent the advantages of the present invention can be exhibited so that the simulated transfer function is free from strict preciseness consequently the implementation thereof can be readily achieved in addition even when a resonant system is constituted between the motor and the load variations in the torque caused.