To produce no adverse effect on other control equipment by preventing fluctuation of the supply voltage when a load is moved and preventing the generation of noise, with saved energy.

A load 6 is advanced by the pressurized fluid supplied from hydraulic pumps 11, 14 to a port 5b on the head side of a differential hydraulic cylinder 5, and thus the quantity of fluid discharged from a port 5a on the rod side becomes equal to the quantity of fluid sucked by a port Y1 of the hydraulic pump 11. By equalizing the quantity of fluid discharged from the port 5b on the head side of the differential hydraulic cylinder 5 to the sum of the fluid quantitites sucked by ports X1, X2 of the hydraulic pumps 11, 14, when the load 6 is retreated the piston rod 5c of the differential hydraulic cylinder 5 smoothly advances or retreats.