An animal litter box has a front-back direction, a left-right direction, and a height direction. The animal litter box includes: a main body that receives excrement of an animal； and a cover that is removably mounted to an upper portion of the main body. The cover includes walls on front-back-direction sides and on left-right-direction sides. The cover includes an open top at a ceiling, the cover includes a cutout in at least one of the walls. The cutout serves as an entrance/exit when the animal enters or exits the animal litter. The cover includes an extending bottom that extends from a lower end portion of the cutout to an inner side of the at least one of walls.
