Abstract: The invention relates to a security material comprising a carrier and at least one photochromic Protein and/or a mutein of a photochromic protein. The security material is characterized in that it comprises at least one irreversible photosensitive layer on the carrier, and the at least one photochromic protein and/or mutein is contained at least in the at least one photosensitive layer and/or in an optional additional layer. The inventive security material is also characterized in that it is highly forgery-proof, the photochromic biomolecule cannot be removed therefrom in a usable form, and the photochromic biomolecule does not need to be supplied to a large group of clients.