Abstract: Provided is a shock absorber in which trivalent chromium is used to achieve both high hardness and low frictional force at a high level without using hexavalent chromium which is suspected of causing damage to the human body and the environment, and a method for manufacturing the shock absorber. A shock absorber (100) of the present invention includes: a cylinder (1) which is filled with hydraulic oil (3); a piston rod (2) which is movable in the cylinder (1); and an oil seal (8) which is fixed to the cylinder (1) and slides on the piston rod (2), in which a hard layer mainly containing chromium obtained from a trivalent chromium plating bath is provided on a surface of the piston rod (2), and the hard layer contains both a crystalline material and an amorphous material, and also contains an additive other than chromium.