An interior body of a disposable diaper includes a liquid-permeable front sheet, a liquid-impermeable back sheet and a liquid-retaining absorbent core. The front sheet has a single sheet including spunbond layers on the front side and back side and a melt blown layer between the spunbond layers. The absorbent core has fiber aggregates and super-absorbent polymer particles. The front sheet is directly bonded to the skin side surface of the absorbent core. The length of the front sheet is longer than the length of the absorbent core, so that the front sheet has extended sections which extend outward in the lengthwise direction from both ends of the absorbent core in the lengthwise direction, while the extended sections are each continuously connected in the transverse direction with the front sheet or back sheet which overlaps with the extended section. The extended sections can directly contact the skin of the wearer.