Inventive disposable underpants are provided with an underpants member formed of a first sheet as an outermost layer and a second sheet located inside the first sheet; an absorbent member provided on the second sheet at the inner side of the underpants member; and a trunk fittable elastic member for fitting the trunk tightly held between the first and second sheets, wherein absorbent member fixing sheets each folded to form an upper and a lower portions are transversely arranged below the absorbent member, and the upper portions of the absorbent member fixing sheets are joined with a lower surface of the absorbent member, whereas the lower portions thereof are joined with an upper surface of the second sheet. Thus, even if the disposable underpants were formed using a thin absorbent member, the absorbent member could suppress a lateral leak of urine without being twisted while the disposable underpants were worn.