Encrypted data player and encrypted data play system

A device and a system for playing encrypted data are provided to obtain a security of a data processor from external intrusion such as hacking by preventing an encrypted key from the outside access when the encrypted data is played. A device key storing circuit(225) stores a device key. A decryption circuit(226) directly receives the device key from the device key storing circuit, decrypts the encrypted key by using the device key, and decrypts the encrypted data by using the decrypted key. The encrypted key and data is received from the same storage medium such as a DVD(Digital Versatile Disk)(210). The device key storing circuit is not accessed from the outside through a system bus. An encrypted data player(220) is a DVD player.