Provided is a disposable diaper (1) having a length direction and a width direction which intersects with the length direction. The disposable diaper (1) is characterized by having an absorbent body (21) which absorbs liquid side flaps (14) which are located on both sides in the width direction and a stretchable member (27) which stretches along the length direction wherein edge sections (14Lg) on the outer sides of the side flaps (14) in the width direction are provided with wavy sections in which protrusions (143a 145a 147a) on the outer side in the width direction and recesses (143b 145b 147b) on the outer side in the width direction are repeated alternately in the length direction and in the width direction the stretchable member (27) is provided either at an inner position (L1) which is located only as far inward from the most recessed point (145d) of the recesses (143b 145b 147b) as an intermediate distance (w1) in the width direction between the most recessed point (145d) and the most protruding point (145c) of the protrusions (143a 145a 147a) or further inward than the inner position (L1).
