A cover includes: a main body that covers the administration section and the first adhesive sheet； and a flange which extends outward from an edge of the main body, the flange being adhered to a portion of the second adhesive sheet which extends outside the first adhesive sheet. A structure composed of the main body and the flange includes: a remaining portion which includes at least a portion of the flange and is designed to be left on the second adhesive sheet； a tear-off portion which includes at least a portion of the main body and is designed to be separated from the remaining portion； and a tear-off assistance portion which facilitate creation of a cut for separating the tear-off portion from the remaining portion.
