A terminal writes first encrypted data in which a communication key and an owner ID are encrypted by using a public key into a second recording medium, and this medium is mounted to a communication apparatus so that the first encrypted data are transmitted to a server. The server sends second encrypted data which it acquires by encrypting a content decryption key by using the communication key which the server acquires by decrypting the received first encrypted data by using a secret key to the communication apparatus, and causes the communication apparatus to record them into the second recording medium. The terminal decrypts a content stored in a first recording medium by using the content decryption key which it acquires by decrypting the second encrypted data read from the second recording medium by using the communication key.