outputted from the position control object 28 is inputted in the position gain setter 31 the position gain setter 31 multiplies the position signal q by a state feedback gain kp related to the position position gain to thereby generate the torque command the torque commands respectively outputted from the gain setters 30 and 31 are added in an adder 32 and subtracted from the torque command u03c4 1 in the adder 26 the torque command u03c4 1 is thus corrected with the state feedback which contributes to improve the stability of the control objects 27 and 28 therefore the gain of the compensators 22 and 24 can be increased so that the suppression performance against the disturbance d can be improved the position gain kp and the velocity gain kv respectively set in advance by the position gain setter 31 and the velocity gain setter 30 may be determined through a designing method based on an optimal regulator the gain of the compensators 22 and 24 in the feedback loop may be determined by increasing the gain to the point where the control system oscillates and multiplying the gain at that point by a predetermined safety factor alternatively a designing method based on an optimal servo control may be adopted to decide the gain of the gain setters 31 and.