DOCUMENT PROCESSOR, DOCUMENT PROCESSING METHOD AND STORAGE MEDIUM STORING DOCUMENT PROCESSING PROGRAM

A document processor has a function of attaching additional information to an electronic document and a function of associating linked information with the additional information. The document processor includes a display unit that displays the electronic document, the additional information, and the linked information, a judging unit that judges whether or not the linked information has changed since it was last referred to by a user, and a display control unit that controls the display unit so that a display state of the additional information varies according to the judgment result from the judging unit.