On the content delivery side, a user management control unit manages authentication information and the distribution of a delivery list at the time of delivering service, the acceptance of a content select request, and charging and settlement on a user basis. On the other hand, an encrypted content control unit creates a content key and an encrypted content using the content key on the basis of a content key creating condition from a copyright owner or copyright manager. Then, an encrypted content key control unit encrypts the corresponding content key using medium information, or medium information and terminal device unique key information presented at the content request, delivers the key to the requester. Then, a content delivery control unit delivers the corresponding encrypted content to the requester at the content request.