PURPOSE: To improve the efficiency and enhance the pressure override characteristic of the circuit in the caption by automatically unloading a counter part pump when only one pump can feed required flow.

CONSTITUTION: The bypass port of a first priority type pressure compensating valve 5 and the pressure reducing port of a second priority type pressure compensating valve 6 are connected to each other by the first bypass line 27 having the first restrictor 7 and the first check valve 9 and the first unloading valve 12 is provided in the first branch line 31 branching from between the first restrictor 7 and the first check valve 9. And the bypass port of the second priority type pressure compensating valve 6 and the pressure reducing port of the first priority type pressure compensating valve 5 are connected by to each other second bypass line 28 having the second restrictor 8 and the second check valve 10, and the second unloading valve 11 is provided at the second branch line 32 branching from between the second restrictor 8 and the second check valve 10. Thereby, since the pump on one side is unloaded when it is not required, the efficiency is improved and the pressure override characteristic is enhanced.