Abstract: A disposable diaper including a panel structure composed of a base sheet and a core attached thereto and a sheet member extending above the panel structure. The panel structure has a pair of first side slaps extending in a longitudinal direction and a pair of end flaps extending in a transverse direction. The sheet member includes a pair of side walls biased to rise above the panel structure and a top wall biased to be spaced upward from the panel structure. The side walls have side edge portions bonded to the vicinity of transversely opposite side edges of the core and first end portions bonded to the end flaps. The top wall has an opening defined between the side walls, second end portions bonded to the end flaps and second side flaps extending outside the top edges of the respective side walls in parallel to the first side flaps. Transversely opposite side edge portion of these flaps overlapping each other in the front and rear waist regions are bonded to each other.