To provide a disposable diaper for pets that fits well around the legs of the pet. A disposable diaper for pets, characterized by a shortest straight line point (300P) being further on a stomach-side waist area (110) side than a diaper center point (100P), and comprising: a rear-side waist area (130); a stomach-side waist area (110); a crotch area (120); a flap section (150) provided in the stomach-side waist area (130) and having an end section in the rear-side direction (130); a diaper longitudinal direction center line (100Y2); the diaper center point (100P); a tail insertion opening (190); an absorbent core (200); an attachment section (300) arranged in the flap section (150); an attachment section intermediate point (300P); an attachment area (900) that receives the attachment section (300); and the shortest straight line point (300P2) being a point on the diaper longitudinal direction center line at the shortest direct distance, via a rear-side end section (150B) of the flap section (150,) in a straight
