Abstract: A system for preventing unauthorized use of digital contents information which disables the use of a storage medium having digital contents recorded thereon by those other than an authorized user. An information terminal 10 reads out digital contents information desired by a user from a contents storing server 6 for storing digital contents information, encodes the read out digital contents information based on ID information of a player 15, and writes it on a predetermined storage medium. The player 15 reads out the data from the storage medium and performs a decode process on the data based on its own ID information to restore the digital contents information.