To hydraulically drive a working device for a hydraulic shovel, without hydraulic piping.

Electrohydraulic units 40 and 40a are used as drive sources for gripping arms 20a and 20b of a gripper 10 as an example of the working device for a hydraulic shovel, and for a revolving mechanism for the gripper. The electrohydraulic units are each an integrated unit of a direct current motor, a hydraulic oil tank, a gear pump, a valve system and a hydraulic cylinder, wherein the direct current motor is rotated by an on-vehicle battery via a control switch to cause the gear pump to pressurize hydraulic oil and telescope a piston rod of the hydraulic cylinder. The electrohydraulic unit 40 opens and closes the gripping arms 20 along arrows E and E1 to grip an object. The electrohydraulic unit 40a rotates a frame 14a and the gripping arms 20 on a rotation axis parallel to the z-axis via a rack 32 and a pinion 33. Two electrical wires laid per electrohydraulic unit suffice for drive control.