In a data management apparatus (1) including a recording device (12) for recording contents data and a data processing section for processing the contents data, first management data for managing the contents data according to a first reference is recorded in the recording device (12), and the data processing section reproduces the contents data based on the first management data, and transfers the contents data to an external device (2) based on second management data which is used for management of the contents data by the external device according to a second reference different from the first reference. As a result, the protection of the contents data can be made while complying with related laws, and the contents data with optional functions added thereto can be backed up.