The present invention is a disposable diaper which has, in a rear waist region, a downwardly openable pocket for holding and retaining waste matter which moves toward a waist opening side. In the disposable diaper (10), the rear waist region (14) has a pocket forming part (20) provided with the downwardly openable pocket (30) which faces in the front-back direction. The pocket forming part (20) has: bilateral fixed parts (45) which are fixed to a band-shaped region (skin contact region) (23) a pocket inner-side region (42) which extends between the bilateral fixed parts (45) and above the portion connecting to the band-shaped region (23) and a pocket outer-side region (43) which faces the pocket inner-side region (42) in the front-back direction across a fold part (33) extending in the horizontal direction (X) and extends toward a crotch region (15), said pocket outer-side region (43) being positioned on an extension of an absorbent body (85). A pocket elastic body (49) which extends in the horizontal direction (X) is disposed in the pocket inner-side region (42). The pocket outer-side region (43) has a portion which is located on the extension of bilateral edges (85c) of the absorbent body (85) and is folded in the horizontal direction (X).本發明之課題在提供一種,在後腰域具備有收容、保持往腰開口側移動的排泄物用的可朝下方開口的口袋之用後即棄式紙尿褲。用後即棄式紙尿褲(10),其後腰域(14)具有口袋形成部(20),該口袋形成部具備有在前後方向對置可朝下方開口的口袋(30)。口袋形成部(20)具有:被固定在帶狀域(23)的兩側固定部(45);在兩側固定部(45)間從與帶狀域(23)連接的部分朝上方延伸的口袋內側域(42);以及口袋外側域(43),其經由往橫向X延伸的彎折部(33)與口袋內側域(42)在前後方向對置往胯下域(15)延伸,且位在吸收體(85)的延長線上。在口袋內側域(42)配置有往橫向X延伸的口袋彈性體(49),口袋外側域(43),是具有往位在吸收體(85)的兩側緣(85c)的延長線上的位置的前述橫向X被彎折的部分。45‧‧‧兩側固定部23‧‧‧帶狀域41‧‧‧帶狀域的中央部14b‧‧‧後腰域的開口緣41b‧‧‧外端部21‧‧‧腰開口14‧‧‧後腰域10‧‧‧用後即棄式紙尿褲31‧‧‧彎折部32‧‧‧口袋兩側域49‧‧‧口袋彈性體33‧‧‧彎折部20‧‧‧口袋形成部43‧‧‧口袋外側域85c‧‧‧兩側緣30‧‧‧口袋15‧‧‧胯下域85‧‧‧吸收體32‧‧‧口袋兩側域41a‧‧‧內端部42‧‧‧口袋內側域78‧‧‧皺褶F‧‧‧方向
