A telescopic shaft includes a hollow outer shaft, an inner shaft spline-fitted to the outer shaft, a resin coating provided on splines on at least one of the outer and inner shafts, and can be extended and contracted in an axial direction. A method for manufacturing the telescopic shaft includes press-fitting the inner shaft into the outer shaft and sliding one of the outer and inner shafts relative to the other of the outer and inner shafts by reciprocating the one shaft in the axial direction. In the sliding, a frequency according to a sliding speed at which the one shaft is slid relative to the other shaft is set to be lower than a predetermined value at the start of sliding, and the frequency is increased in a continuous or stepwise manner when a sliding load of the one shaft to the other shaft is reduced.