PURPOSE: To reduce the number of times of occurrence of a last-off stoppage condition by restarting up a system after stopping it transiently and changing a control condition, and reducing transmission data quantity to an image buffer when the last-off stoppage condition occurs.

CONSTITUTION: A resolution conversion circuit 9, when the image data buffer 7 being filled and no more data being accumulated, converts the resolution of binary data transmitted from an image processing circuit 6, and converts the data transmitted in, for example, 800dpi to 40Odpi. When a last-off stopping state where the image data buffer 7 is filled and no more data can be accumulated occurs, a signal representing such state is transmitted to a control part. After last-off stoppage is performed in such way, the control part decreases the speed of an original carrier motor (or phototelectric reading unit carrier motor) to 1/n, for example, 1/2, and decreases the resolution conversion ratio of the resolution conversion circuit 9 to 1/n. for example, 1/2.