A shock absorber includes a cylinder in which a working fluid is sealed, a piston rod movable into and out of the cylinder, the piston rod extending from the cylinder, a piston disposed inside the cylinder, the piston being configured to partition a first fluid chamber and a second fluid chamber, and a choke portion formed by penetration of a seamless choke passage, the seamless choke passage being configured to allow the first fluid chamber to communicate with the second fluid chamber.