PURPOSE: To arbitrarily increase a damping force variable range on the compression side by disposing a valve on the compression side to a piston, forming a bypass passage in a piston rod, disposing a check valve, opened to a lower working oil chamber side, in a reservoir chamber, and arranging a valve, used in common on the expansion side and the compression side, between an upper working oil chamber and a reservoir chamber.

CONSTITUTION: During a compression stroke in a soft mode wherein a variable control orifice 18 is maximized through operation of a switch valve 16, a whole amount of oil extruded from a lower working oil chamber B flows through a bypass passage 14 to an upper working oil chamber A without passing the valve 13 on the compression side of a piston 2. Further, oil in an amount equivalent to an entrance volume of a piston rod 4 flows herefrom to the reservoir chamber C side through a communicating passage 27 as a valve 30 used in common on the expansion side and the compression side, the oil being supplied to the lower working oil chamber B through the check valve 8 of a base valve 9. In a hard mode, a whole amount of oil flowing out from the lower working oil chamber B side opens the valve 13 on the compression side of the piston 2 and flows to the upper working oil chamber A side, and is similarly supplied to the lower working oil chamber B.