The cover member mounted on a toilet sheet spread over a floor surface and absorbing excreta from a pet, is provided to have a configuration that first members each having a bottom surface for contact with a floor surface are disposed in a first end region of the bottom section, ribs each having a bottom surface, at least a portion of the bottom surface being for contact with a top surface of the toilet sheet, are provided in a middle region, and second members each having a bottom surface for contact with a top surface of the toilet sheet are provided in a second end region.