An open-type disposable diaper (1) having a longitudinal direction and a width direction intersecting with each other, having arranged a first waist-circumference part (1a), a crotch part (1b), and a second waist-circumference part (1c) in this order from one side in the longitudinal direction, including an absorbent body core (41), and a pair of fastening tapes extending outward from the first waist circumference part in both width directions, wherein the second waist-circumference part includes an engaging end (1c1) of the fastening tapes at a location in the longitudinal direction where longitudinal ends, of the fastening tapes, on a side of the crotch part are located when longitudinal ends of the disposable diaper are aligned, the absorbent body core includes at least a pair of notch parts (43, 44) on both ends in the width direction (431, 441), and in the longitudinal direction a portion that becomes narrowest among portions of the absorbent body core sandwiched between the pair of notch parts is located in a region, in an area between the engaging end and a product center (b) that is a center of the disposable diaper, between a center of the area and the engaging end.
