A flat type disposable diaper 1 having a liquid permeable topsheet 2, a liquid impermeable or repellent backsheet 3, a liquid retentive absorbent member 4 interposed between the two sheets, a pair of anti-leakage cuffs 6 having standing gather-forming elastic members 61, and a pair of leg flaps 7 having leg gather-forming elastic members 71. The diaper 1 is sectioned into a front section A, a crotch section B, and a rear section C along the longitudinal direction. The absorbent member 4 includes a higher weight region 4A and a lower weight region 4B. The lower weight region 4B is located in the rear section C, and the higher weight region 4A is located in the crotch section B. At least one of the standing gather and the leg gather is substantially absent in the rear section C having the lower weight region 4B.本發明之展開型丟棄式尿褲1,具備液體透過性之正面薄片2、液體不透過性乃至斥水性之背面薄片3、以及介於兩薄片間之液體保持性吸收體4,且沿長度方向,具有含有立體縐褶形成用彈性構件61之一對防漏翻邊6、6及含有腿部縐褶形成用彈性構件71之一對腿部褶片部7、7,且區分為腹側部A、股下部B、及背側部C。吸收體4具有高基重區域4A及低基重區域4B,將低基重區域4B設置於背側部C,將高基重區域4A設置於股下部B;於設置有低基重區域4B之背側部C實質上不形成上述立體縐褶及上述腿部縐褶。1...展開型丟棄式尿褲2...液體透過性正面薄片3...液體不透過性乃至斥水性背面薄片6...防漏翻邊7...腿部褶片部11...背側部C中之尿褲長度方向之端緣13...黏扣帶14...定位區61...立體縐褶形成用彈性構件62...防漏翻邊形成用薄片材63...立體縐褶中之背側部C側端緣71...腿部縐褶形成用彈性構件73...腿部縐褶中之背側部C側端緣
