PURPOSE: To make an outer tube lighter in weight as well as to improve the extent of riding quantity by joining a rod guide and a packing gland both to an opening end of a cylinder tube, and making input load so as not to be largely transmitted to the outer tube, in a shock absorber which is formed into a double cylinder structure.

CONSTITUTION: An outer tube 4 is installed on the circumference of a cylinder tube 1, and each small diametral part at both vertical ends is fitted in an outer circumferential mounting part 7c of a packing gland 7 and an outer circumferential mounting part 11a of a spacer 11 in a state of making them slidable in the axial direction. When load acts on a rod guide 6, the cylinder tube 1 receives this tensile load, but at the side of the outer tube 4, it is absorbed by axial sliding motion at the small diametral part, so that the tensile load will not be received by the outer tube 4 at all. With this constitution, since rigidity of the outer tube can be set to be low, it is made up of resins, through which a decrease in cost by means of promotion of large lightweightiness, reduction in material percentage and omission of rust prevention painting is well promotable and, what is more, working becomes facilitated in this way.