To prevent excessive force acting from an actuator to an equipment by performing a feedback control for an operating part based on positional information on the detected operating part and pressure information on pressure oil for operating the operating part.

When an opening/closing control of a valve 15 is performed, opening of the valve 15 is detected by an opening sensor 23 and hydraulic fluid pressure supplied from servo valves 19 within hydraulic chambers 16, 17 to a hydraulic cylinder 11 is detected by pressure sensors 25, 26. When pressure is in a normal state, a feedback control is performed for opening of the valve 15 based on a valve opening signal 24. When the valve 15 is in an abnormal state such as excessive load, the abnormal state is detected by the pressure sensors 25, 26 and the corresponding pressure signals 27, 28 are supplied to a controller 20. The controller 20 performs feedback controls for the valves 19 so that hydraulic fluid supplied to the cylinder 11 may be set pressure or below. As a result, excessive force which is more than required one is not imparted from the cylinder 11 to the valve 15 and an adverse effect on the valve 15 is prevented.