PURPOSE: To eliminate any damage and noise of a hydraulic device and improve the operational feeling thereof, by communicating the hydraulic operating fluid of an actuator to an oil tank and increasing the stroke volume of a hydraulic motor when the hydraulic motor is stopped.

CONSTITUTION: A high pressure selective means 46 is constituted with a counter balance 22 arranged in a hydraulic circuit 20 and a pressing means 49 is provided on a volume control member 40, and when a hydraulic motor 24 is stopped, the hydraulic operating oil of an actuator 36 is bypassed to an oil tank 25 and a volume control member 40 is so pressed as to increase the stroke volume of the hydraulic motor 24. In as much as abnormal brake pressure force can thus be prevented from occurring in the conduit of the hydraulic motor 24 when the hydraulic motor 24 is stopped on the high speed side, any damage and noise of the hydraulic device can be eliminated and the operation feeling thereof can be improved.