PURPOSE: To obtain multiplex spring characteristics by filling and arranging elastic body between two members of rigid body for forming fluid chambers which pressure fluid can be fed into and exhausted from and cavities which are squashed elastically by expansion of the fluid chambers, on a bush inscribed in the title used for the suspension device of a vehicle.

CONSTITUTION: Elastic body 15 of rubber or the like is filled up between an outer tube 11 and an inner tube 14 arranged concentric to each other for forming fluid chambers 16a, 16b by hollowing out two places which are on the axial line of an arm 10 and in symmetry about a center axis to form cavities 17 penetrating in the axial direction in four places near said chambers. Still more, respective fluid chambers 16a, 16b are connected to an oil pump 22 via the first, the second electromagnetic valves 18, 20 and a pressure regulating valve 21 to make switching of an oil passage for controlling liquid pressure for the fluid chambers 16a, 16b with a controller 25 in accordance to the action of the arm 10. Therefore, multiplex spring characteristics are obtained, electrical control can be done and riding comfortability and controllability of a vehicle can be made good.