An animal toilet having a front-rear direction, a right-left direction and a height direction comprising: a urine passing part that is provided with a plurality of holes through which urine passes and on which an excrement treatment material is to be placed; an absorbent body setting part that is provided below the urine passing part and on which an absorbent body is to be placed; an opening part that is provided above the urine passing part and allows an animal to come in and out; and side walls provided on both right and left sides of the opening part, the animal toilet further including: a cover; an upper container; a lower container; and a tray, the urine passing part being provided to the upper container, the absorbent body setting part being provided to the tray, the opening part being provided to the cover, the side wall including a part of the cover, a part of the upper container and a part of the lower container, characterised in that: a maximum height of the side wall in a forward area that is located forward of a center position in the front-rear direction being smaller than a minimum height of the side wall in a rearward area that is located rearward of the center position, a maximum opening width of the opening part in the forward area being larger than a maximum opening width of the opening part in the rearward area, and in the cover, a maximum inward inclination of the side wall in the forward area is smaller than a maximum inward inclination of the side wall in the rearward area. a urine passing part that is provided with a plurality of holes through which urine passes and on which an excrement treatment material is to be placed; an absorbent body setting part that is provided below the urine passing part and on which an absorbent body is to be placed; an opening part that is provided above the urine passing part and allows an animal to come in and out; and side walls provided on both right and left sides of the opening part, the animal toilet further including: a cover; an upper container; a lower container; and a tray, the urine passing part being provided to the upper container, the absorbent body setting part being provided to the tray, the opening part being provided to the cover, the side wall including a part of the cover, a part of the upper container and a part of the lower container, characterised in that: a maximum height of the side wall in a forward area that is located forward of a center position in the front-rear direction being smaller than a minimum height of the side wall in a rearward area that is located rearward of the center position, a maximum opening width of the opening part in the forward area being larger than a maximum opening width of the opening part in the rearward area, and in the cover, a maximum inward inclination of the side wall in the forward area is smaller than a maximum inward inclination of the side wall in the rearward area. a cover; an upper container; a lower container; and a tray, the urine passing part being provided to the upper container, the absorbent body setting part being provided to the tray, the opening part being provided to the cover, the side wall including a part of the cover, a part of the upper container and a part of the lower container, characterised in that: a maximum height of the side wall in a forward area that is located forward of a center position in the front-rear direction being smaller than a minimum height of the side wall in a rearward area that is located rearward of the center position, a maximum opening width of the opening part in the forward area being larger than a maximum opening width of the opening part in the rearward area, and in the cover, a maximum inward inclination of the side wall in the forward area is smaller than a maximum inward inclination of the side wall in the rearward area. a maximum height of the side wall in a forward area that is located forward of a center position in the front-rear direction being smaller than a minimum height of the side wall in a rearward area that is located rearward of the center position, a maximum opening width of the opening part in the forward area being larger than a maximum opening width of the opening part in the rearward area, and in the cover, a maximum inward inclination of the side wall in the forward area is smaller than a maximum inward inclination of the side wall in the rearward area.