This disposable diaper (10) is provided with a leg extension/contraction section that can extend/contract along the product lengthwise direction and is disposed along a leg-encircling opening section provided at the outside in the product widthwise direction with respect to an absorbent body. The leg extension/contraction section is provided with: a band-shaped first leg extension/contraction material (76)； and a thread-shaped second leg extension/contraction material (77) that is disposed within a first extension/contraction material disposing region at which the first leg extension/contraction material has been disposed, and that has a shorter length in the product widthwise direction compared to the first leg extension/contraction material. A non-extending/-contracting side flap (70) is provided to the skin-contacting surface side with respect to the first leg extension/contraction material and/or the second leg extension/contraction material. The elongation rate in the product lengthwise direction of the second leg extension/contraction material is higher than the elongation rate in the product lengthwise direction of the first leg extension/contraction material.
