1. A document processing apparatus for associating an electronic document stored in a storage device with written-in information added to a document which is a printer output of said electronic document, the apparatus comprising: information adding means for adding identification information to the electronic document to identify said electronic document when printing said electronic document stored in said storage device; document printing means for printing said document which has said identification information added; document reading means for reading said printed document which has new written-in information added, and for generating image information; information extracting means for extracting identification information added to said electronic document from said image information, and associating said stored electronic document with said image information; receiving means for communicating with a composite device, for receiving print item selection information from the composite device and for outputting said received print item selection information, said print item selection information indicating any one of: (a) only written-in information; (b) only an original document; and (c) a document in which written-in information has been reflected as a printing object; written-in note extracting means coupled to said receiving means for receiving said print item selection information outputted from said receiving means and for, in a case wherein said print item selection information indicates either of only written-in information or a document in which written-in information has been reflected as a printing object, comparing the electronic document identified by identification information extracted by said information extracting means with said image information, extracting said written-in information newly added to the document, and storing said written-in information as image data, and wherein said written-in note extracting means does not compare the electronic document with said image information if the print item selection information indicates only an original document; text conversion means for converting text-convertible written-in information out of said extracted written-in information into text data from one written-information after another, and storing said text data; means for laying out said image data or text data of said stored written-in information on a print document, and generating a print document of a new output type; and means for outputting the generated print document to said composite device.