1. An information device security management method which can limit access to certain information by use of fingerprint authentication, the security management method comprising a fingerprint authentication step of performing fingerprint authentication, and, if fingerprint authentication fails for a predetermined number of times, enabling PIN code authentication; and, after the fingerprint authentication step is switched to PIN code authentication, a PIN code authentication step of performing PIN code authentication, and, if PIN code authentication fails for a predetermined number of times, enabling an authentication failure flag such that only the authentication by means of fingerprint authentication can be performed.