Disclosed is a data management apparatus comprising a message transfer/analysis unit that receives an object data access request from a client and returns a response; an object metadata storage unit that stores, as metadata, a set of ancillary information on data for an object and a data area corresponding to the ancillary information; an object metadata management unit that performs reading, updating, and registration processing for the metadata; a data conversion unit that sends the data access request to a data access unit, extracts object data; and a data access unit that sends a data access command, specified by the data conversion unit, to a file server or a database server and sends response data, received from the file server or the database server, to the data conversion unit.