In a disposable diaper, a ventral-side outer sheet and a back-side outer sheet are separated at a crotch portion, the back-side outer sheet has a main unit section that corresponds to joined sections in an up-down direction and a back-side extension section that extends below the back-side main unit section, the ventral-side outer sheet is composed of only a ventral-side main unit section that corresponds to the joined sections in the up-down direction, the back-side extension section has a central portion in the width direction overlapping the absorber and hip cover portions extending on both sides of the central portion in the back-side main unit section.
