Provided is an unfolding-type disposable diaper (1) which has a mutually intersecting length direction and width direction, and in which a first waist section (1a), a crotch section (1b), and a second waist section (1c) are aligned from one side in the length direction. The disposable diaper has an absorbent body core (41) and a pair of fastening tapes (10) which extend from the first waist section (1a) to the outside on both sides in the width direction. The second waist section (1c) has fastening tape engagement ends (a, 1c1) at the position in the length direction at which the crotch-section-side end of the fastening tapes (10) in the length direction is located when both ends of the disposable diaper (1) in the length direction are aligned. The absorbent body core (41) has, on both ends in the width direction, at least a pair of cutouts (43). In the length direction, among the region between a product center (b), which is the center of the disposable diaper (1), and engagement ends (a, 1c1), a section (43a) of the absorbent body core (41) where the width thereof is narrowest among the sections of the absorbent body core (41) sandwiched between the pair of cutouts (43) is positioned in a region (A2) between the center (c) and the engagement ends (a, 1c1) of said region.
