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.用後即棄式紙尿布(1)係具備有沿著設在比起吸收體更靠近製品寬度方向外側的腳圍開口部配置，並沿著製品長度方向可伸縮之腳伸縮部。腳伸縮部係具備有：帶狀的第1腳伸縮材(76)；及配置在配置有第1腳伸縮材的第1腳伸縮材配置區域內，且比起第1腳伸縮材，製品寬度方向的長度短之線狀第2腳伸縮材(77)。在比起第1腳伸縮材及/或第2腳伸縮材更靠近肌膚抵接面側，設有非伸縮性的側翼片(70)。第2腳伸縮材的製品長度方向之伸長率係較第1腳伸縮材的製品長度方向之伸長率高。
