Abstract: In a dot pattern, both sufficient strength during the use of a diaper and the ease of tearing can be achieved, while inhibiting sticking of fiber waste of a non-woven fabric in the sealing device. The problems can be solved by the underpants-type disposable diaper characterized by a side seal section 13 is formed in a dot pattern in which a plurality of rows of dot-shaped welded parts 13s, 13b, disposed with intervals in a vertical direction, are disposed in a transverse direction, and non-welded parts 13n, disposed all over in the transverse direction, are disposed on both sides of each welded part 13s, 13b, in the vertical direction; the side seal section 13 has at least partly in the vertical direction a non-densely welded region LD and a densely welded region HD; and each welded part 13b in the densely welded region HD is larger in area than each welded part 13s in the non-densely welded region LD.

Abstract: In a dot pattern, both sufficient strength during the use of a diaper and the ease of tearing can be achieved, while inhibiting sticking of fiber waste of a non-woven fabric in the sealing device. The problems can be solved by the underpants-type disposable diaper characterized by a side seal section 13 is formed in a dot pattern in which a plurality of rows of dot-shaped welded parts 13s, 13b, disposed with intervals in a vertical direction, are disposed in a transverse direction, and non-welded parts 13n, disposed all over in the transverse direction, are disposed on both sides of each welded part 13s, 13b, in the vertical direction; the side seal section 13 has at least partly in the vertical direction a non-densely welded region LD and a densely welded region HD; and each welded part 13b in the densely welded region HD is larger in area than each welded part 13s in the non-densely welded region LD.