This invention provides a pants-type disposable diaper (1) with the objective of maintaining a relatively high joining strength in the upper joined part while limiting the feeling of discomfort experienced by a wearer or a caregiver upon contact with the joining section, wherein the pants-type disposable diaper (1) comprises a ventral part (2) and a dorsal part (3) that are joined to one another by a joining section (5L). The width direction (W) end portion (2L) of the ventral part and the width direction end portion (3L) of the dorsal part, the respective inner surfaces of which are superimposed so as to face one another, are joined to one another via a plurality of fused portions (11) that are aligned and spaced apart from one another in the longitudinal direction (L), thereby forming the joining section. The width direction tensile stress in the upper joined part (P5U) of the joining section is greater than the width direction tensile stress in the lower joined part (P5L) of the joining section. The width direction dimension of a margin (12) in the upper joined part is larger than the width direction dimension of the margin in the lower joined part. The respective surface areas of the fused portions located in the upper joined part are larger than the respective surface areas of the fused portions located in the lower joined part.
