PURPOSE: To enable the adjustment of a vehicle height to be carried out without changing riding comfortableness by supporting the spring end part on a cylinder side by a spring receiver, and enabling both a cylindrical body and a stopper for regulating the fully extended position of a piston rod to be together moved in the axial direction.

CONSTITUTION: A piston 2 is inserted into a chamber in which oil O is filled. Between a piston rod 3 to which piston 2 is connected and a cylinder 1, a spring 4 is interposed. A cylindrical body 11 is screwed on the other circumference of the cylinder 1, so that it can be displaced at an optional position in the axial direction. Both ends of the coil spring 4 are supported by spring receivers 9, 10. A stopper 14 regulates the springing-out of the piston rod 3 by lockedly engaging the piston 2 with a cushioning material 14a. The upper surface of the stopper 14 is abutted on a collar 15 so as to be engaged with a hook 11a, so that the stopper 14 can be prevented from being sprung out. Thus, the adjustment of vehicle height can be enabled without changing riding comfortableness.