Intermediate shaft and method for manufacturing same

A powder coating is affixed by the powder fluidization immersion method to the surface (17a) of an outside spline (17) or an inside spline and caused to melt and flow in a state in which a crosslinking agent of a thermoplastic resin contained in the powder coating is carried on the surface (17a) in advance. The thermoplastic resin is then crosslinked by the crosslinking agent and a resin coating layer (20) is formed.