PURPOSE: To prevent an image registered in a disk from learning no marker trace by changing a threshold level up to a level for discriminating marker density as white and reading it again, and recording it in the disk.

CONSTITUTION: This device is provided with a system control board 6, and when a scanner can discriminate only white and black, a marker is set to half tone and a marker position is discriminated as a difference of reflection density. Subsequently, the marker is erased from a registered image, and also, in order that a position can be designated by the marker, first of all, a scan is executed by the same operation as usual, and the image is dropped into a page memory. Also, a page to be read is advanced, and when the marker is detected, memory storage of its page is suspended, and only data in the marker position is held. The same page is read by raising a binarized threshold level to an extent that the marker can be erased this time, expanded to the page memory, marker data read beforehand from this image is cut off, the whole image is stored in a disk, and the threshold level is returned to its original level.