A stretch band (12) having a continuous band shape is formed by sandwiching elastic stretch members (15 19) between a first sheet material (12S) and a second sheet material (12H) and without joining superimposed areas of the first sheet material (12S) and the second sheet material (12H) at either edge in the CD direction joining the materials in an area therebetween. This stretch band (12) is cut at the midpoint in the CD direction between the elastic stretch members (15 19) at a joined location of the first sheet material (12S) and the second sheet material (12H) forming a pair of divided stretch bands (12f 12b). The CD direction positions of these divided stretch bands (12f 12b) are reversed or these divided stretch bands (12f 12b) are each flipped vertically such that a stomach side exterior body (12F) and a back side exterior body (12B) are formed by the pair of divided stretch bands (12f 12b).
