An electronic information backup system for safely back up electronic value information about electronic money and electronic ticket through communication in a server so as to exclude unauthorized actions when backup and restoring are performed and for restoring the electronic value information from the backup in case of emergency such as loss of key information. In this system, electronic value information is encrypted, the encrypted electronic value information is registered in an electronic safe server, and the user receives the registration, presents the registration to the server to receive the encrypted electronic value information, and decrypts the electronic value information with decrypting key data. The decrypting key can be kept in another server. The electronic value information and the decrypting key can be kept separately in different servers. It is possible to keep the sequence of number of the cryptogram to serve as the basic the decrypting key in the server, and to generate a decrypting key according to a decrypting key generation algorithm on the terminal side. In case of loss of the decrypting key, the possessor certificate information is verified and then the user can receive the decrypting key from the server.