PURPOSE: To perform smooth, high-precise, and stable control of the speed and the pressure of various machines by performing control of the longitudinal moving mechanism of a fluid holding part through longitudinal movement of a converting mechanism occasioned by rotational movement of an electric motor, based on a fluid pressure in a fluid holding part.

CONSTITUTION: In a process wherein resin is plasticized and metered, an electric motor 9 is rotated to rotate a plasticizing screw 5 after the plasticizing screw is moved backward through reversing of an electric motor 15, and the tip of the plasticizing cylinder 4 is filled with resin molten by a heater 6. In a process wherein resin is injected in the cavity of a mold 1, the electric motor 15 is controlled based on detected signals from the pressure detector 28 of an oil pressure source 25 and the position detector 29 of the plasticizing screw 5. In this case, in an oil pressure control mode, an oil pressure flow rate direction control valve 27 is released to discharge working oil in an oil pressure cylinder 21 to the interior of an oil tank 26, and a piston 22 is brought into contact with the dead end of the oil pressure cylinder 21.