To enable to form an unvulcanized rubber skin with a homogeneous width so as to obtain a good surface appearance of a side wall of a retreaded tire after vulcanization.

A narrow width unvulcanized rubber strip 3 is stuck to a side surface area of a base tire obtained by removing a rubber skin. An unvulcanized rubber strip part 3b laminated after a second lap is bonded in spiral-form under overlapped with a laminated unvulcanized rubber strip part 3a in an inner side previously. A convergent parts 3c, 3d whose width are progressively reducing toward an each inner end 8 position and outer end 10 position are provided to a part including the outer end 10 of the unvulcanized rubber strip 3 and a part including the inner end 8 thereof.