A document processing apparatus comprises an image reader for scanning an original manuscript which is not updated to generate first image data on the original manuscript and for scanning an updated manuscript to generate second image data on the updated manuscript, a text information extraction part for extracting first text information from the first image data and extracting second text information from the second image data, an updated portion detector for detecting an updated portion of the updated manuscript on the basis of the first text information and the second text information, an electronic document generator for generating an electronic document of the updated manuscript on the basis of the second image data, and a storage controller for generating display data of the updated portion on the basis of a detection result on the updated portion and storing the display data into the electronic document.