PURPOSE: To restrict the speed of other actuators from slowing down as well as to restrain increase of load pressure generated at the time of starting an actuator which is connected to a heavy load, by providing a plunger to press down a pressure compensation spring in response to the pressure from a sequence valve and a restrictor equipped downstream from the sequence valve.

CONSTITUTION: When an excessive load is applied to an actuator provided with a sequence valve 13, among a plural number of actuators driven by virtue of the pressure from a variable capacity pump 9, the load pressure to the actuator raises to a specified pressure and a sequence valve 13 opens. In order for a plunger 12 to press down pressure compensation springs 5, 6, which are housed in pressure compensation valves 3, 4, by virtue of the load pressure supplied from the sequence valve 13, the established pressure for the pressure compensation valves 3, 4 rises, whereby reduces the pressure differential between nose in front and rear or directional control valves 7, 8 and regulates the pressure added to the actuator. Thus operating speed of other actuators can be prevented from slowing down as well as excessive increase of load pressure on the actuator, on which excessive load is added, can be restrained.