A pet diaper adapted to be fastened around a pets rear and under the tail, and to the pets waist such that the pet diaper is securely positioned to receive and contain fecal droppings. The pet diaper comprises a frame structure which supports a container that is lined with a replaceable plastic bag. The pet diaper is affixed to the pet using adjustable straps which wrap around the pets midsection and attach to the collar. The frame structure holds the bag away from the pet to prevent expelled fecal matter from getting on the pets fur.