A piston rod is supported free to slide without using a guide bush so that there is no risk of the guide bush falling out. Also, costs are reduced and oil leakage is prevented by eliminating additional procedures such as caulking. The piston rod, which has excellent durability, is allowed to slide smoothly over a long period of time without generating noise. For this purpose, in a bearing unit for a single cylinder type hydraulic damper or gas spring, or a multi-cylinder type hydraulic damper comprising seal members 55, 56, 57 and 64, and a rod guide 6, the rod guide 6 comprises a cylindrical engaging part 13 which engages with a cylinder 2, a cylindrical bearing part 16 which guides a piston rod 5, and a bearing layer 15 fixed to the inner circumferential surface of the cylindrical bearing which slides on the outer surface of the piston rod. The bearing layer is previously fixed only at a position of a base material comprising a thin steel plate which becomes the cylindrical bearing part, and the rod guide is formed in a one-piece construction by press-molding or deep-drawing this base material.