A pet house includes a housing structure, an engaging member, and an auxiliary carrier. The housing structure includes a bottom plate, four surrounding side plates, and a top portion. The inside of the housing structure is formed with an accommodating space which can communicate with the outside of the housing structure through an opening. One of the surrounding side plates and the top portion includes an engaging structure which is detachably engaged with the engaging member, and the engaging member can be engaged with the engaging structure of another pet house. The auxiliary carrier is disposed in the accommodating space. The auxiliary carrier can be placed on the bottom plate when the auxiliary carrier is disposed in the accommodating space. The auxiliary carrier can be disposed in the accommodating space when two of the bottom plate, the surrounding side plates, and the top portion are separated from each other.
