A distributed data storage unit (11) stores music data including one or more contents (42) and billing information (43). A purchase process unit (13) obtains a process right to the music data through communications. A data conversion unit (14) separates the billing information (43) from the music data that can be processed with the obtained process right, and converts the resultant data into an internal format. The converted music data is stored i n an internal data storage unit (15). At the same time, the data conversion un it (14) extracts decryption keys from the billing information (43), and records the extracted decryption keys in a copyright management table (16). A contro l unit (17) carries out uniform copyright management using the copyright management table (16) and instructs a playback unit (18) or a check-out/chec k- in unit (19) to process the converted music data.
