4. The document management device according to claim 1 , wherein the parent generation document is used as the base to determine the additional information extracted by the difference extracting unit.
1. A document management device, connected to a plurality of reader terminals via a network, for managing a document circulated to a reader in accordance with a circulation tree and additional information added to the document by the reader, the circulation tree indicating a circulation order of a plurality of readers, and each of the plurality of readers belonging to one of at least a first group and a second group, the device comprising: a storing unit operable to store document data of a document that is circulated from a reader based on the circulation order of the circulation tree; a reader identification information acquiring unit operable to acquire reader identification information of a reader from an input process via a console or a reader terminal by the reader; a process receiving unit operable to receive a process with respect to the document data of the document that is stored in the storing unit; a status storing unit operable to store the received process as a status in association with the reader identification information; a notification unit operable to notify a storing location of the document to the console or the reader terminal based on the status stored in association with the reader identification information, the reader identification information being acquired; a document acquiring unit operable to acquire a document data of the document by scanning a print of the document, or by receiving the document that is sent from the reader according to the notification, to store the document data in the storing unit; a difference extracting unit operable to extract additional information added by a reader associated with the selected reader terminal to document data of the document or print of the document; a setting unit operable to set a parent generation document for each group to which the reader belongs, the parent generation document being used to be associated with the additional information extracted by the difference extracting unit; and an additional information management unit operable to store the additional information extracted by the difference extracting unit in association with the parent generation document set for each group by the setting unit.