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).一種具有:長方向、以及與前述長方向交叉的寬幅方向之用後即棄式紙尿布,其特徵為具有:吸收液體的吸收體;位在前述寬幅方向的兩側部的側翼;以及沿著前述長方向伸縮的伸縮構件,前述側翼的前述寬幅方向外側的端緣部,是具備於前述長方向交替重複有在前述寬幅方向外側形成凸狀的凸部與在前述寬幅方向外側形成凹狀的凹部的蛇行狀的蛇行狀部分,前述伸縮構件在前述寬幅方向,被設在從前述凹部的凹部頂點以前述凹部頂點與前述凸部的凸部頂點的前述寬幅方向中的頂點間距離位於內側的內側位置、或比該內側位置更被設於內側。1‧‧‧紙尿布3‧‧‧前部5‧‧‧胯下部7‧‧‧後部12‧‧‧中央帶狀區域14‧‧‧側翼15‧‧‧腿褶邊16‧‧‧腿側摺邊16a‧‧‧支點16b‧‧‧內側頂點18‧‧‧腰褶邊21‧‧‧吸收體23‧‧‧防漏薄片24‧‧‧背面薄片25‧‧‧伸縮薄膜26‧‧‧肌膚側薄片26A‧‧‧接合部27‧‧‧絲橡膠28‧‧‧腰褶邊薄膜29‧‧‧目標帶片30‧‧‧扣帶211b‧‧‧皺襞部211f‧‧‧皺襞部CL‧‧‧中心位置W‧‧‧製品寬幅方向
