Provided is a disposable undergarment which can prevent the leakage of bodily fluids by fitting the edge of the leg openings to the body of the wearer, and without exposing the buttocks while being worn. The disposable undergarment (10) of the present invention comprises: an annular elastic waist panel (12) obtained by joining a front waist panel (18) and a rear waist panel (19)； and a crotch panel (13) that has an absorbent (11) and which is connected to the elastic waist panel (12). A pair of leg opening edges (23) are formed by the inner edges of the front and rear waist panels (18, 19) and both vertical side edges (43c) of the crotch panel (13). The crotch panel (13) is equipped with a pair of leg sheets (43) which extend in a vertical direction and which are connected to both side edges (11c, 11d) of an absorbent (11). Each leg sheet (43) has an inner area (57a) which adjoins the absorbent side, and an outer (57b) which adjoins the inner area (57a). The inner area (57a) stands up with respect to the absorbent (11) at the side edges (11c, 11d) of the absorbent (11) to reach the edge of the leg opening (23), and the outer area (57b) protrudes to the outside of the undergarment (10) in the lateral direction (X) to form the leg opening edge (23).L'invention concerne un sous-vêtement jetable qui peut empêcher la fuite de fluides corporels en adaptant le bord des ouvertures de jambe au corps du porteur et sans exposer les fesses lorsqu'il est porté. Le sous-vêtement jetable (10) de la présente invention comprend : un panneau de taille élastique annulaire (12) obtenu en reliant un panneau de taille avant (18) et un panneau de taille arrière (19) ； et un panneau d'entrejambe (13) qui a un absorbant (11) et qui est relié au panneau de taille élastique (12). Une paire de bords d'ouverture de jambe (23) sont formés par les bords internes des panneaux de taille avant et arrière (18, 19) et les deux bords latéraux verticaux (43c) du panneau d'entrejambe (13). Le panneau d'e
