A cord reinforcing layer 30 can be highly efficiently fanned with easy control, and the amplitude and the wavelength of a wavy steel cord 32 can be made uniform throughout the cord reinforcing layer.When the wavy steel cord 32 (ribbon-like body 37) is wound plural times around the forming drum 35 to form the cylindrical cord reinforcing layer 30, the amount of extension is made decreased with distance from a set position P of a bead core 12 in the axial direction, and the amount of extension applied in advance to the wavy steel cord 32 in the vicinity of the set position P is approximated to the amount of extension according to the expansion and deformation of the wavy steel cord 32 at a position spaced away from the set position P, whereby at least either one of the amplitude and the wavelength of the wavy steel cord in the tire can be made uniform throughout the cord reinforcing layer 30.