The purpose of the present invention is to provide a cover member for a toilet seat and to provide a pet toilet using same, whereby displacement of the pet toilet seat is prevented and urine on the seat is contained. The cover member (130) which absorbs pet excrement and is placed upon a toilet seat (120) lain on a floor surface has a configuration whereby: a first end-side area (143) in a base (132) has arranged therein a first member having a lower surface for coming in contact with a floor surface； an intermediate area (163) has provided therein ribs (164) having a lower surface (165) that at least partly come in contact with the upper surface of the toilet seat (120)； and a second end-side area (153) has provided therein a second member for coming in contact with the upper surface of the toilet seat (120), in the lower surface thereof.本發明之目的在提供一種，防止寵物用如廁薄片的偏移且攔阻薄片上的尿之如廁薄片的蓋構件及使用該蓋構件的寵物用便器。亦即，將被載置在舖設在地面吸收寵物的排泄物的如廁薄片(120)上的蓋構件(130)作成，底部(132)的第1端側區域(143)配設有第1構件，其是具有與地面接觸用的下面，中間區域(163)設有肋(164)，其是讓至少一部分接觸如廁薄片(120)上面用的下面(165)，第2端側區域(153)，是在下面設置有與如廁薄片(120)上面接觸用的第2構件之結構。
