The present invention is an animal litter box (1) configured to have a front/rear direction, a left/right direction, and a height direction, and provided with the following: a urine passage section (21) to which a plurality of holes (210) through which urine passes are provided, and in which an excrement treatment material is installed an absorber installation section (31) which is provided lower than the urine passage section (21) and in which an absorber is installed an opening (41) which is provided higher than the urine passage section (21), and through which an animal enters and exits and a side wall (4a) provided to both left and right sides of the opening (41). A maximum height (H1) of the side wall (4a) in a front region (11) further frontward than a middle position (C) in the front/rear direction is smaller than a minimum height (h2) of the side wall (4a) in a rear region (12) further rearward than the middle position (C), and a maximum opening width (W1) of the opening (41) in the front region (11) is greater than a maximum opening width (W2) of the opening (41) in the rear region (12).一種動物用便器,具備前後方向、左右方向、及高度方向,且具備:尿通過部(21),設有供尿通過的複數個孔(210),且設有排泄物處理材料;吸收體設置部(31),係設在比尿通過部(21)更下方,且設置有吸收體;開口部(41),係設在比尿通過部(21)更上方,用以供動物進出;以及側壁(4a),係設在開口部(41)的左右兩側,該動物用便器(1),在比前後方向的中央位置(C)還前方的前方區域(11)中之側壁(4a)的最大高度(H1),係小於比中央位置(C)還後方的後方區域(12)中之側壁(4a)的最小高度(h2),前方區域(11)中之開口部(41)的最大開口寬度(W1),係大於後方區域(12)中之開口部(41)的最大開口寬度(W2)。1‧‧‧動物用便器2‧‧‧上容器3‧‧‧托盤4‧‧‧外罩4a‧‧‧側壁4b‧‧‧折入部5‧‧‧下容器21‧‧‧尿通過部22‧‧‧底面部23‧‧‧側面32‧‧‧把手41‧‧‧開口部42‧‧‧側壁部43‧‧‧前方壁部44‧‧‧後方壁部45‧‧‧伸出部54b‧‧‧凹部210‧‧‧孔431‧‧‧前表面部432‧‧‧上表面部451‧‧‧嵌合片451a‧‧‧貫通孔562a‧‧‧凸部22a‧‧‧中央11‧‧‧前方區域12‧‧‧後方區域220‧‧‧傾斜部C‧‧‧中央位置
