A disposable diaper includes: a main body, a side flap, and a pair of fastening tapes. The main body includes a liquid permeable topsheet, a liquid impermeable outer sheet, and an absorber between the topsheet and the outer sheet. The side flap covers one of edge portions of the main body in a longitudinal direction and has a greater dimension in a width direction than the main body. The fastening tapes are attached to respective edge portions, in the width direction, of the side flap and configured to be fastened onto a fastening portion on an opposite one of the edge portions of the main body. One of edge portions of the absorber in the longitudinal direction is located inboard of an outer imaginary line connecting outermost points of the fastening tapes in the longitudinal direction.
