PURPOSE: To obtain an illegal behavior preventing seal which does not generate an error due to its clear signature by certifying the validity of the signature by the signature overlapped with the number and the prefix added to on the seal or outside of the seal.

CONSTITUTION: A single card consisting of a partially transparent adhesive ink form and is provided with a transparent carrier on its one side and provided with a line for protecting an adhesive layered covered on the thin film on the other side. For example, the card consists of three cards 6 to 8 each of which consists of a carrier consisting of the sheet-like transparent plastic material 9 to 9", the adhesive ink form sticking on to each linear 11 to 11'' protecting the adhesive layer and the lustrous multi-layered thin film 10, 10'. Then the same number displays each thin film of the cards 6 to 8, and this number desirably consists of a prefix 13 consisting of the alphabet of two continuous characters, is normally displayed at the corner of the thin film and consists of a corresponding number 12.