PURPOSE: To adapt brake control to turning characteristics by connecting a parking brake to a pressurized doil supply circuit for a hydraulic motor through a valve to operate the valve for supplying high pressure side oil in the circuit to said brake.

CONSTITUTION: A turning parking brake 12 is connected to a pressurized oil supply circuits 4, 6 for a hydraulic motor 3 through a manual selector valve 16. The valve 16 is in the brake releasing position (g) so long as it is not operated. When pressurized oil is supplied to one of said circuits 4, 6 to drive the motor 3, high pressure oil is supplied from a shuttle valve 15 to the brake 12 through the valve 16 to release the brake 12, and maintained as it is by a check valve 16a. To operate the brake 12, the valve 16 is changed over to the brake position (h). While the supply of high pressure oil is interrupted, pressurized oil in the brake 12 is unloaded through an oil circuit 17. Thus, the brake 12 is set to the operative condition.