To avoid an abnormal rise of the pressure of an air chamber accompanied by the reduction of a volume of the air chamber behind a free piston caused by some reasons such as the seep-in of fluid.

The hydraulic shock absorber 10 is provided with a check valve 100 opened to permit the release of the pressure from the air chamber 73 behind the free piston 60 to a reservoir 30 when the pressure of the air chamber 73 behind the free piston 60 is raised beyond a predetermined value in a communication route 90 for making the air chamber 73 behind the free piston 60 in a cylinder tube 16 communicate with the reservoir 30.