This diaper (1) for underweight infants has: an exterior sheet (24) disposed on the non-skin side of an absorbent body (21)； and a belt member (30) provided with joining members (31) located on one side and the other side in the widthwise direction therereof. The belt member (30) is joined to the non-skin side of the exterior sheet (24) by the joining member (31) on said one side, and an additional connection part (70) for detachably connecting a part of the belt member to the exterior sheet (24) is provided in a region on said one side of the belt member (30).[課題]提供一種穿用時，帶構件不易從本體部脫離的低體重兒用的紙尿布。[解決手段]一種低體重兒用紙尿布(1)，係具有：被配置在較吸收體(21)靠非肌膚側的外裝薄片(24)、以及在寬邊方向的一方側及另一方側具備卡止構件(31)的帶構件(30)，其中，前述帶構件(30)，是藉由前述一方側的前述卡止構件(31)卡止在前述外裝薄片(24)的非肌膚側，在前述帶構件(30)的前述一方側的區域，設有將前述帶構件的一部分可剝離地與前述外裝薄片(24)加以接合的追加接合部(70)。
