A disposable diaper (10) includes a pair of leg stretch units (75) extending along the leg opening (35) and can expand and contract in the product longitudinal direction. A separation distance (D2) between the ends the leg stretch units (75) in the rear waistline region 30 is longer than the separation distance (D1) between the ends of the leg stretch units (75) in the front waistline region (20). The leg stretch units extending from the crotch region towards the rear waistline region are convex outwardly in the product widthwise direction. The leg stretch units extending from the crotch region towards the front waistline region are convex towards an inner side in the product widthwise direction.