To reduce a shock generated at the time of switching of control over the servo system using the servomotor by reducing the discontinuity of a torque command when the control mode is switched from a torque control mode to a position and speed control mode.

As for the control over the servo system using the servomotor, the servomotor is driven by being supplied with the torque command in the torque control mode, the value of the integrator 3 of a speed loop for the speed control mode is rewritten into the value of the torque command of the torque control, and the value of the integrator 3 in the torque control mode is always set to the same value with the torque command. When the control mode is switched from the torque control mode to the position and speed control mode, the torque command value of the torque control which is rewritten in the torque control mode is outputted as the value of the integrator 3 of the speed loop to the motor, which is driven with this torque command value. Consequently, the continuous torque command value is supplied to the motor at the time of the switching of the control mode.