A disposable diaper (1) having a longitudinal direction and a width direction intersecting the longitudinal direction, the disposable diaper includes: an absorbent body (21) that absorbs liquid flaps positioned in both side portions in the width direction and a stretchable member that stretches along the longitudinal direction, end edge portion (14Lg) in an outer side in the width direction of the side flap (14) having a wave form part that is a wave form in which a projected portion (143a) projected to the outer side in the width direction and a depressed portion (143b) depressed to the outer side in the width direction are repeated alternately in the longitudinal direction, stretchable member being provided, in the width direction, in either one of an inner side position (L1) and a further inner side than the inner side position, the inner side position being away from a depressed portion tip (145d) of the depressed portion (145b) to an inner side by a distance between tips (w1), the distance between tips being a distance between the depressed portion tip and a projected portion tip (145c) of the projected portion (145a) in the width direction.
