The present invention includes a hydraulic source (28), at least a plurality of work hydraulic cylinders (11) of a single type, that are to be driven with pressure oil from the hydraulic source (28), a control valve (22) that controls a flow of pressure oil from the hydraulic source (28) to the work hydraulic cylinders (11), an operating means for (26) issuing a command for drive of the control valve (22), a selector switch (41, 42) that selects at least an independent operation of the work hydraulic cylinders (11), and a pressure oil control means (12a, 12b, 34 to 37) for allowing the pressure oil to flow to a work hydraulic cylinder (11) selected with the selector switch (41, 42) and disallowing flow of pressure oil to other work hydraulic cylinders (11). <IMAGE>