An animal litter box (1) includes: a main body part (10) that receives excrement of an animal； and a cover part (20) that is removably mounted to an upper portion of the main body part (10). The cover part (20) includes wall parts (21) on front-back-direction sides and on left-right-direction sides, and the cover part (20) has an open top at a ceiling. The cover part (20) has a cutout (25) in at least one location in the wall parts (21) provided on front-back-direction sides and on left-right-direction sides, and the cutout (25) serves as an entrance/exit when the animal enters or exits the animal litter box (1). The cover part (20) includes an extending bottom part (26) that extends inward with respect to the wall part (21), from a lower end portion (25eb) of the cutout (25).
