To provide a data encryption device and its method that is made to eliminate a possibility of an infringement of copyright by use of duplicated data when the data of which the copyright is established is duplicated.

A data processing device 1 comprises a central processing unit 2 which executes each software, a program store unit 3 which temporary stores software and data produced by the software, a characteristic data store unit 4 which contains individual data to distinguish the data processing devices 1 individually, an internal storage 5 that is a nonvolatile memory media, and a control unit 6 that is connected electrically with each component, performs control instructions, and transfers data, or the like. The characteristic data store unit 4 comprises non-rewritable memory media such as so-called ROM, and an individual data from each data processing device is kept to store before shipment of a product, or the like.