PURPOSE: To suitably execute the control to restrict the overshoot of a ram in the case of the load being eliminated suddenly like punching of using the ram of a hydraulic press.

CONSTITUTION: Four proportional sheet valves V1 to V4 are connected so as to make a full bridge circuit onto a circuit connected to a hydraulic cylinder 2 to move a ram 1 up and down and a hydraulic pump 3, etc. The action timing of the proportional sheet valves V1 to V4 is controlled with an NC controller 9. Usually, by controlling the proportional sheet valves V2, V3 by on-off and meter out control, applying the hydraulic pressure PU to an upper chamber 2U of the hydraulic cylinder 2, moving a piston 10 downward and driving the ram, the material is punched. The self running state of the ram at a moment of the material being punched is detected with the NC controller 9, at the moment, a pilot valve 8 of the proportional sheet valve V1 is driven, the back pressure PL of a lower chamber 2L side of the hydraulic cylinder 2 is controlled, the self running of the ram 1 is restricted.