To provide a disposable diaper for pets that fits well around the waist of the pet. A disposable diaper for pets, having: a rear-side waist area (130) a stomach-side waist area (110) a crotch area (120) a rear-side flap section (160) a stomach-side flap section (150) and a tail insertion opening (190). At least either the rear-side flap section (160) or the stomach-side flap section (150) have an identification area (10A). A determination can be made that there is a problem with the state of the rear-side flap section (160), on the basis of visual inspection information about the identification area (10A), said visual inspection being performed externally on the disposable diaper for pets (10).
