A method of manufacturing a hydraulic shock absorber is provided with a piston main body manufacturing step 21 including the process of sintering of the piston main body and the process of forming of the molded sealing are performed, a piston assembly manufacturing step 22 including process of forming of the throttle oil passage on the piston main body manufactured in the piston main body manufacturing step 21 and the assembly of valves onto the piston main body, and a hydraulic shock absorber manufacturing step 23 for manufacturing a hydraulic shock absorber using the piston assembly. In this manner, it is not necessary to provide for an intermediate inventory between each process. Furthermore inventory monitoring processes are simplified in the piston main body manufacturing step and productivity is increased since it is not necessary to monitor the inventory level with respect to a plurality of piston assembly types with different valves or throttle hydraulic passages.