To improve comfortableness by reducing responsiveness to an input of high frequency vibration of an unsprung section without sacrificing suppression effect toward rolling and pitching.

Piston lower chambers 22 of right and left twin tube type gas filled hydraulic shock absorbers 10 and 11 communicate to an oil chamber 36 of a gas type accumulator 14 through conduits 12 and 13. A selector valve 15 including a spool 42 operated by receiving pilot pressure on both ends through pilot passageways 49 and 50 each branched from the conduits 12 and 13 is annexed to the accumulator 14. When the right and left shock absorbers 10 and 11 operate in a negative phase, the spool 42 is moved by the pressure difference and cuts off the communication between one of the conduits 12 or 13 and the accumulator 14, thus generating high damping force at the cut off side hydraulic shock absorber 10 or 11 for suppressing rolling and pitching. When high frequency vibration of an unsprung section is inputted, the oil liquid inflow towards both ends of the spool 42 is suppressed by throttles 53 and 54 provided at pilot passageways 49 and 50 for maintaining communication between the accumulator 14 and both conduits 12 and 13.