1. A document processing apparatus for associating an electronic document stored in a storage device with written-in information added to a document as a printer output of said electronic document, comprising: information adding means for adding identification information to an electronic document to identify said electronic document when printing said electronic document stored in said storage device; document printing means for printing said document added with said identification information; document reading means for reading said printed document added with new written-in information and 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; written-in note extracting means for comparing an 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 each of written-in information as image data; 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; and 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.