A method is provided which enables to know a location of copied document data without the use of a server or others. Document data that is data used for reconstructing a document is managed by combining, in one document object, the document data along with relationship information for identifying other document data generated by reproducing the document data. Likewise, when a reproduction processis performed, the other document data is managed by combining, in one document object, the other document data along with relationship information for identifying the reproduction.