To improve a shock absorber that is interposed between a vehicle body and a wheel to attenuate the road surface vibration to be input in the wheel.

A shock absorber includes a shock absorber body in which a wheel side tube 2 is slidably inserted in a vehicle body side tube 1 via a pair of upper and lower bearings 30, 31, the upper and lower bearings 30, 31 are mounted on an inner circumference of the vehicle body side tube 1, and a lubrication space 3 is formed between the bearings 30, 31, a damper 4 contained in the shock absorber body, a reservoir chamber formed between the shock absorber body and the damper 4 and consisting of a gas chamber G and a hydraulic fluid chamber R, a rod guide 6 for demarcating a hydraulic fluid chamber R in upper and lower sections (R1, R2), a flow path L having a check valve 6 for permitting only the movement of the hydraulic fluid from the upper hydraulic fluid chamber R1 to the lower hydraulic fluid chamber R2, and a communication hole 2a for communicating the lower hydraulic fluid chamber R2 with the lubrication space 3. A communication passage 90 is formed parallel to the sliding space 9 which is formed between an inner circumference of the upper bearing 30 and an outer circumference of the wheel side tube.