A document management section 77 updates and manages stored information in an additional information storage section 74 in such a manner that when details of operation information having been acquired in an operation information acquisition section 71 regard an operation of reading all the pages that is an operation targeting all the pages of an unread document, the current status of processing of the document is changed from unread to read, whereas when the details of operation information regard an operation of reading a part of the pages that is an operation targeting a part of the pages of an unread document, the current status of processing of the document is changed from unread to hold. By this means, a current status of a management target document that changes every moment can be updated and managed in detail in real time.