The present invention provides a data management apparatus for managing a plurality of data items output by a plurality of communication devices that output data. The data management apparatus includes a storage section configured to store device identification information of each of the plurality of communication devices in association with charge identification information including either contractor identification information of a contractor of a contract for using a relay apparatus that is configured to transfer the plurality of data items to the data management apparatus or acquirer identification information of a data acquirer who acquires the data from the data management apparatus, and a charge amount determination section configured to determine a charge amount for each item of the charge identification information on the basis of data communication traffic volumes corresponding to data output from the communication devices of one or more device identification information items stored in association with the charge identification information.