PURPOSE: To improve a machine tool in machining accuracy by providing a stepwise-feeding auxiliary cylinder for transferring the load of a workpiece on the machine tool in the hydraulic circuit, and utilizing the pressurized area difference between the hydraulic actuator and the auxiliary cylinder in order to adjust the stepwise feeding quantity.

CONSTITUTION: The auxiliary cylinder 12 is operated to deliver the oil flowing from a rod side chamber 12b of the auxiliary cylinder 12 to a head side chamber 9a of a cylinder 9 on which load is applied. The area of the head side chamber 9a is made larger than that of the auxiliary cylinder 12 to obtain a larger piston stroke of the auxiliary cylinder 12. Consequently, the movement of the cylinder 9 on which load is applied magnified, so that a highly accurate stepwise feeding can be obtained. Varying the stroke of a rod 12c by adjusting the distance between the rod 12c of the auxiliary cylinder 12 and a bolt 13a of a stopper 13 permits the stepwise feeding quantity to be readily changed.