A method of manufacturing a spline telescopic shaft includes a masking step in which, in a prescribed axial-direction region (L1; L2) of an intermediate manufacturing product, partial tooth grooves (G) that are equally spaced circumferentially are respectively covered by masking members (70; 70P; 70Q; 70R; 70S) that are equally spaced circumferentially; a resin coating step in which a resin layer (43A; 53PA) is formed, and inner surfaces of the partial tooth grooves (G) covered by the masking members (70; 70P; 70Q; 70R; 70S) are left as metal exposed portions (44; 54P) that are equally spaced circumferentially; and a coating film forming step in which, in a state where the intermediate manufacturing product provided with the resin layer (43A; 53PA) is centered with respect to a broach (80; 80P) via the metal exposed portions (44; 54P), the intermediate manufacturing product and the broach (80; 80P) are caused to slide relative to each other in an axial direction by press-fitting such that the resin layer (43A; 53PA) is shaved to form a resin coating film (43; 53P).
(Figure 5)