PURPOSE: To provide a driving circuit for a hydraulic driving device with a compact size and a low manufacturing cost by providing a second communication passage passing an inside of a valve body and an external passage, independently on a first communication passage passing an inner passage of the valve body at the communication time of piping in a directional changeover valve.

CONSTITUTION: When a directional changeover valve 40 is at an interruption position, a pump and motor lines 18, 20 form closed loops 50, 52 while being interrupted therebetween. When the directional changeover valve 40 is shifted to a communication position, the lines 18, 20 are communicated with each other through first and second communication passages I, II. Pressure oil from a hydraulic pump 14 is supplied to a hydraulic motor 16 for rotating it, and circulated to a tank 12 thorugh a return line 22. A supply amount Q of the pressure oil is set to be a sum of a reference flow rate Q1 passing a first communication passage I and an addition flow rate Q2 passing a second communication passage II. The directional changeover valve is remarkably reduced in its size, and is integrated with the hydraulic motor to reduce the required space and a manufacturing cost.