Abstract: A data copyright management system in one embodiment includes a database for storing original data, a key control center for managing crypt keys, copyright management center for managing data copyrights, and a communication network for connecting these sections. Data supplied from the database to users is encrypted and distributed. The user decrypts the encrypted data by crypt keys obtained from the key control center or copyright management center. When a user stores, copies, or transfers data, the data is encrypted by a different crypt key. This disclosure can be applied to a data copyright management system for using not only single data but also a plurality of data supplied from a single database or a plurality of data supplied from a plurality of databases.