A disposable diaper for pets, comprising: a back-side waist area a stomach-side waist area a crotch area both end sections in the diaper longitudinal direction both end sections in a diaper longitude-intersecting direction a tail insertion opening an absorbent core an area not having the absorbent core arranged therein an attachment section provided in the stomach-side waist area an attachment area that accepts the attachment section an expandable/contractible elastic member for legs, arranged, in the extended state, in a prescribed area in the diaper longitudinal direction, between the absorbent core and an end section in the diaper longitude-intersecting direction a leg gather formed by the contraction of the expandable/contractible elastic member for legs and a standing-up section in which the end sections in the diaper longitudinal direction stand up as a result of the contraction of the expandable/contractible elastic member for legs.
