A housing for small pet animals includes a pedestal portion 1, a fixing side plate 3 uprightly attached to the pedestal portion 1, an activity wheel 5 with one side opened toward the fixing side plate 3 and the other side closed by closing members 52c. The wheel 5 is disposed above the pedestal portion 1 with the one side closed by the fixing side plate 3. The housing further includes a housing equipment immovably attached to the fixing side plate 3 and disposed in a housing space surrounded by the fixing side plate 3 and the activity wheel 5.