PROBLEM TO BE SOLVED: To provide a disposable pull-up diaper whose breathability is improved and whose material cost is reduced and so on by reducing the weight per unit area of nonwoven fabric used for the diaper while preventing the fusion cutting or the poor strength of welding parts formed in edge parts on both the right and left sides of the main front part and the back part.SOLUTION: In this disposable pull-up diaper, reinforcing sheets 6 made of the nonwoven fabric are imparted to only a region including the right and left side welding parts 5 and the vicinities of the side welding parts 5 right and left two by two, and are welded to a sheet made of the nonwoven fabric constituting the front main part 3 and the back part 4 to reinforce the side welding parts 5. The reinforcing sheets 6 are positioned between outer sheets 21 and inner sheets 22 of exterior materials 13 in the region including the right and left welding parts 5 in the front main part 3 and the vicinities thereof.
