Both high air permeability and high peeling strength are achieved. The above problem is solved by providing an underpants-type disposable diaper including a stretchable region (80) stretchable at least in one direction in an outer body (20), in which the stretchable region (80) is formed by stacking an elastic film (30) between a first sheet layer (20A) composed of a nonwoven fabric and a second sheet layer (20B) composed of a nonwoven fabric, and in a state in which the elastic film (30) is stretched in the stretching and contracting direction, the first sheet layer (20A) and the second sheet layer (20B) are joined via through holes (31) formed in the elastic film (30) at a large number of sheet bond portions (40) arranged at intervals in each of a stretching and contracting direction and a direction orthogonal thereto, and in the sheet bond portions (40), the first sheet layer (20A) and the second sheet layer (20B) are joined at least by a melted and solidified material (30m) of the elastic film (30) among the first sheet layer (20A) and the second sheet layer (20B).
