Abstract: A pet diaper holder uses disposable human diapers. The diaper holder includes upper and lower flexible holder portions joined at one side. The upper holder portion overlays the rump of the animal, including the base of the animal's tail. The lower holder portion holds the diaper against the belly and groin area of the animal, and extends between the animal's rear legs to overlay the base of the animal's tail from below. The upper and lower holder portions define a rearward opening through which the tail of the animal protrudes and openings surrounding the rear legs of the animal. Snap-fitting male and female connectors join the holder portions at an openable side and at the opening surrounding the base of the tail, and fasten the waistbands associated with the diaper to the lower holder portion thereby avoiding shifting and balling of the diaper with movement of the animal.