setting the incomplete integration term contained in the integration gain at an optimum value conforming to the mechanical system fig1 is a block diagram illustrating an embodiment of the invention fig2 a is a circuit diagram of the fig1 embodiment for an analog servo system and fig2 b is graph illustrating the state of an optimum torque command in the fig1 embodiment an embodiment of the present invention will now be described in detail with reference to the drawings fig1 is a system block diagram for realizing control with a digital servo system numeral 1 denotes a mechanical system which is the object of control here an input output relationship is stipulated by a transfer function which includes a coefficient typified by motor inertia j m a move command inputted to this servo system is applied to an adder circuit 2 together with a backlash correction signal or a pitch error correction signal the adder circuit computes an error e p between the command and a position signal fed back from a linear scale such as an inductsyn or a pulse coder an arithmetic block 3 including a position gain k p computes a velocity command from the error e p and inputs the velocity command to an adder circuit 4 which computes an error e v between the command and a velocity signal fed back from a pulse coder numeral 5 denotes a velocity control block having a transfer function in which the incomplete integration term thereof is varied depending upon whether the error e p is zero or not the output of this velocity control block 5 determines via a current control.