An electronic terminal performs early detection of unauthorized analysis thereon and prevents unauthorized acquisition and falsification of confidential information that is not to be released to a third party. The electronic terminal stores confidential information that is protected by consecutive application of a plurality of protection measures for defense against an attack from a third party. The electronic terminal monitors for attacks to the protection measures from an external source, and upon detecting an attack on one protection measure, updates a protection state of the confidential information to a new protection state in which either a new protection measure has been added to a protection path from the one attacked protection means to the confidential information, or the one protection measure on the path has been updated to a higher defense level.