A manufacturing method for a telescopic shaft that comprises a male shaft having a non-circular outer circumferential shape; a female shaft having a non-circular inner circumferential shape that fits around the male shaft so that relative sliding movement in the axial direction is possible, and so that rotation torque can be transmitted; and a coated section that is formed on the outer circumferential surface of the male shaft or the inner circumferential surface of the female shaft, and reduces sliding resistance between the male shaft and the female shaft; the manufacturing method comprising the steps of: forming the coated section on the outer circumferential surface of the male shaft or the inner circumferential surface of the female shaft, the coated section having a thickness that has a sliding resistance that is at least greater than the lower limit value of an allowable range for a specified sliding resistance, and that generates interference when the female shaft is fitted onto the male shaft; fitting the female shaft onto the male shaft after the coated section has been formed such that the shafts are in a state of interference; and causing the male shaft to slide back-and-forth a specified number of times in the axial direction with respect to the female shaft while heating the coated section with a heating apparatus, causing the coated section to be heated and expand by the heat that is transmitted from the heating apparatus and the friction heat that is generated due to the interference, and causing the coated section to plastically deform, which reduces the interference and sets the sliding resistance between the male shaft and the female shaft within the specified allowable range for the sliding resistance, characterized in that after fitting the female shaft onto the male shaft, grease having hardness in the range of NLGI consistency number of class 1 to class 3, is filled between the coated section and the inner circumferential surface of the female shaft or the outer circumferential surface of the male shaft, and the male shaft is caused to relatively slide back-and-forth in the axial direction with respect to the female shaft after the grease has been filled. forming the coated section on the outer circumferential surface of the male shaft or the inner circumferential surface of the female shaft, the coated section having a thickness that has a sliding resistance that is at least greater than the lower limit value of an allowable range for a specified sliding resistance, and that generates interference when the female shaft is fitted onto the male shaft; fitting the female shaft onto the male shaft after the coated section has been formed such that the shafts are in a state of interference; and causing the male shaft to slide back-and-forth a specified number of times in the axial direction with respect to the female shaft while heating the coated section with a heating apparatus, causing the coated section to be heated and expand by the heat that is transmitted from the heating apparatus and the friction heat that is generated due to the interference, and causing the coated section to plastically deform, which reduces the interference and sets the sliding resistance between the male shaft and the female shaft within the specified allowable range for the sliding resistance, characterized in that after fitting the female shaft onto the male shaft, grease having hardness in the range of NLGI consistency number of class 1 to class 3, is filled between the coated section and the inner circumferential surface of the female shaft or the outer circumferential surface of the male shaft, and the male shaft is caused to relatively slide back-and-forth in the axial direction with respect to the female shaft after the grease has been filled.