The present invention relates to a document editing and a printing apparatus comprising a data processor such as a personal computer and a word processor, and more particularly to a method of correcting data to be printed. The object of the present invention is to provide a printed data correcting method capable of correcting an error in a printed document during printing without terminating the printing when such error is found. In order to achieve the object, according to the present invention, data involving printing is displayed to the user. Each data is stored which is indicative of whether data of a specified unit such as a character, a line or a page are printed or print-waiting such that the data stored as being print-waiting can be corrected. When the data stored as being already printed are corrected, only the page which contains the corrected data is reprinted.