A crotch member that has a good fit and prevents leakage of excrement while being band-shaped, and a disposable underwear including the crotch member are provided. A crotch member 4 of a disposable underwear 1 is joined along the left and right side edges of a ventral joint part J1, a dorsal joint part J2, and a belt-like crotch member 4. At least a pair of crotch side edge elastic members 25a having a gap with the side joint portion J2, and the crotch side edge elastic members 25a are joined to the crotch member 4 at the center side with respect to the crotch side edge elastic members 25a. It includes at least a pair of ventral-side connecting elastic members 25b that overlap with the portion J1, do not overlap the back-side end portion with the back-side joining portion J2, and have stronger tension than the crotch-side edge elastic member 25a. [Selection] Figure 3【課題】帯状でありながら、フィット性が良く、排泄物の漏れを防止できる股部材及び該股部材を備えた使い捨て下着を提供する。【解決手段】使い捨て下着１の股部材４は、腹側接合部Ｊ１と、背側接合部Ｊ２と、帯状の股部材４の左右側縁に沿って接合され、各腹側接合部Ｊ１及び背側接合部Ｊ２との間に間隙を有する、少なくとも一対の股部側縁弾性部材２５ａと、股部側縁弾性部材２５ａより中央側で股部材４に接合され、腹側端部が腹側接合部Ｊ１と重なり、背側端部が背側接合部Ｊ２と重ならず、股部側縁弾性部材２５ａより張力が強い、少なくとも一対の腹側接続弾性部材２５ｂとを含む。【選択図】図３
