To make a device simple in constitution, and unselective in work liquid.

A ball screw 3 is secured to the output shaft 1a of an power motor 1 via a reduction gear 2, and a nut member 4 threadedly engaged with the screw 3 is fixed to one end of the cylinder rod 5a of a first liquid-operated cylinder 5. A second liquid-operated cylinder 6, having an area ratio equal to that of the head and rod sides of the cylinder 5, is provided to communicate the head and rod sides of both the cylinder 5 and 6 by a head side liquid- operated piping 7 and a rod side liquid-operated piping 8 respectively; and also the rotation direction, speed, and torque of the motor 1 is controlled by a controller 9. Inside sliding parts are only the O rings fitted to the cylinder rod 5a and a cylinder rod 6a, and the inner wall of a cylinder bore, consequently water containing no abrasion resistant additive can be used as hydraulic fluid.