PURPOSE: To make it possible to perform the partial segment of a picture and a reencoding processing after an editing using a small memory at a high speed even if the picture is one from a large-sized binary picture.

CONSTITUTION: A binary picture compression/extension processor 10 encodes a starting line by a code word having no correlation in a vertical direction by the instruction of a horizontal mode instruction circuit 17, stores the other lines as the code data encoded by a prescribed code word and stores code position data showing the starting position of the code word corresponding to the starting line as an intermediate start table, for plural areas (partial image) obtained by dividing all the pictures every prescribed number of line. At the time of segmenting the partial messages, an extension processing only for the necessary partial image is performed based on the code data and encoding position data. At the time of also encoding the image for which an editing, etc., was performed, a compression processing is performed only for the partial image and the image is connected with unedited code data.