PROBLEM TO BE SOLVED: To safely and reliably install a radio communication medium as personal identification means based on biological information, in a living body.SOLUTION: A flexible and thin film-like radio communication medium 1 is formed by an antenna 2 obtained by forming a foil-like conductive material having biocompatibility in a loop, and a communication medium 9 embedded by a material having biocompatibility, and then the radio communication medium 1 is embedded in the periodontium by a process of surgical operation treatment of an intraoral mucous tissue. A telephone unit which is wirelessly connectable to the radio communication medium installed in the periodontium as personal identification means based on biological information, automatically recognizes authentication means by making a receiver approach the radio communication medium in addition to calling upon arrival and determines use propriety of the telephone in order to allow telephone conversation. Further, utilization permission is limit
