To provide a driving structure of a double acting hydraulic cylinder capable of securing the expansion/contraction of the hydraulic cylinder excellent in the high-speed responsiveness.

Double-position switching valves 27, 29 provided with valve pads 27a, 29a to be communicated with a pump port 26 and valve parts 27b, 29b to be communicated with a tank port 28 are respectively interposed in an oil passage A leading to a cell on a cap side of a double-acting hydraulic cylinder 12 and an oil passage B leading to a cell on a head side of the hydraulic cylinder, and the hydraulic cylinder 12 is expanded/contracted by switching an unload valve 31 connected between common oil passages 30, 31 leading from ports 26, 28 to the switching valves 27, 29.