Provided is a disposable diaper with an improved fit. This disposable diaper (10) is provided with a front waist-surrounding region (11), a back waist-surrounding region (12), a crotch region (13), and an absorbent structure (21) extending from the crotch region to the front and back waist-surrounding regions. The absorbent structure is provided with an absorbent body (22) and extensions (31) extending outwardly from both side edges (23) of the absorbent body in the lateral direction. The extensions are made of a laminate of sheet materials and are provided with a longitudinally extending distal edge (32) that is spaced apart from a side edge of the absorbent body in the lateral direction, a cuff separating line (33) extending between the side edge of the absorbent body and the distal edge, a leg gather section (41) extending between the cuff separating line and the distal edge, and a leak-preventing cuff section (51) starting from the cuff separating line. The leak-preventing cuff section has a free edge (52) that is parallel to and spaced apart from the cuff separating line. The distance between the cuff separating line and the distal edge is greater than the distance between the cuff separating line and the free edge. The number of sheet materials in the leg gather section is greater than the number of sheet materials in the leak-preventing cuff section.
