comparator 7 then the detected value and the set value of the screw position are compared and calculated by the comparator 7 to thereby generate a deviation d to an adder subtractor device 8 in the device 8 the deviation d is added to or subtracted from the switching over position set values for the filling pressure and or speed and the holding pressure outputted from a switching over position setter 6 thus correcting the set values corrected set values are applied from the device 8 to a sequencer 21 and then a pressure control valve 10 and or flow regulating valve 12 and driven through an amplifier 9 39 thereby performing the switching over control between the filling pressure and or speed and the holding pressure as is well known in the art the control valve 10 is connected to a fluid passage between a pump 11 and a flow regulating valve 12 and the pressure is selectively applied to the ram cylinder to displace the ram 3 fig4 shows the switching over position between the filling pressure and or speed and holding pressure when corrected with the deviation d si is the filling pressure and or speed change over position and si 39 is the corrected position sh is the holding pressure change over position set by the setter 6 and sh 39 is the corrected position so is the screw foremost position in the conventional control.