To provide a disposable diaper for a low-weight infant with improved fitness of an absorbent core for allowing low-weight infants to easily move their legs.SOLUTION: A disposable diaper 1 for a low-weight infant includes an absorbent core 2 with a narrow width part in a central part in a longitudinal direction. The doubly-folded diaper 1 is pressed against an upper surface of a base with a skin side surface down while being spread and extended in the longitudinal direction, and then, the diaper is returned to a natural state after placing a plate and a weight. The absorbent core 2 has a first region S1 along the upper surface and a second region S2 separated from the upper surface upward, and the other folding lines FLa which are boundaries between the first region S1 and the second region S2 are formed.SELECTED DRAWING: Figure 9【課題】低体重児が脚を動かしやすく吸収性コアのフィット性を向上させた低体重児用の使い捨ておむつを提供する。【解決手段】長手方向の中央部において幅狭部を有する吸収性コア２を備える低体重児用の使い捨ておむつ１であって、二つ折りされているおむつ１を、長手方向に展開かつ伸長した状態で、肌側面を下にして台の上面に押しつけた後に、板及びおもりを載せた後、自然状態にしたとき、吸収性コア２は、上面に沿う第１領域Ｓ１と、上面から上方に離間している第２領域Ｓ２とを有し、第１領域Ｓ１と第２領域Ｓ２との境界となる別の折り線ＦＬａが形成されている。【選択図】図９
