In the second valve group, feeder passages 36a, 36b to 38 of the directional control valves 25 to 27 are connected in parallel with respect to the second hydraulic pump 11 through a second parallel passage 43 so that the hydraulic fluid from the second hydraulic pump 11 is supplied to the directional control valves 25 to 27 in parallel. Also, the directional control valve 24 is connected in parallel to the feeder passage 36a of the directional control valve 25 and the directional control valves 26, 27 through the parallel passage 43, while it is connected in tandem to the feeder passage 36b of the directional control valve 25 so that the hydraulic fluid from the second hydraulic pump 11 is supplied to the directional control valve 24 with priority. The feeder passage 36b of the directional control valve 25 is also connected to the first parallel passage 40 through a fixed throttle 19.