To provide a cylinder device capable of increasing reliability in strength by increasing the rigidity of a spring receiver against an input into a spring.

A hydraulic shock absorber is formed by fitting a bell-shaped spring seat 10 (spring receiver) to one end part of the cylinder 1 from which a piston rod 3 is extended. The spring seat 10 is axially arrested by bringing a plurality of recessed seats 13 formed in the tip end part of the spring seat into contact with the upper end of a cylinder 1, and radially arrested by bringing a plurality of radially inward extension parts 15 formed by equally disposing in a tubular part 14 thereof in the circumferential direction into contact with the outer peripheral surface of the cylinder 1. The extension parts 15 are formed at the terminal end portion (lower side in Fig. 1) formed integrally with a flange part 11, the fixed part of the spring seat 10 to the outer peripheral surface of the cylinder 1 is moved close to the flange part 11 receiving the input into the spring, and the bearing force of the spring is increased while eliminating the shortage of the rigidity of the spring seat 10 against the input into the spring.