Provided is a disposable diaper in which the fitting performance of a waistband can be improved while any sense of discomfort caused by the outer edge of the waistband abutting against the wearer's body is suppressed. A disposable diaper (10) has: an absorbent body (11)； a waistband (80) having a band extension and contraction region (R80) that is located on the skin surface side relative to a skin-surface-side sheet in a rear trunk region and that extends and contracts in the width direction； and a flap part having a joint region (75) joined to the absorbent body, a flap extension and contraction region (76), and a locking section (73). The waistband has: a first base end part (87) and a second base end part (84) joined to the skin-surface-side sheet； and a standing part (85) folded back to the rear side in a folded line (FL) in the front side relative to the first base end part (87) and the second base end part (84). The flap part is at least partially disposed between the skin-surface-side sheet and the waistband. The outer edge of the waistband is disposed in a region overlapping with the joint region.
