Abstract: A liner scanning device for a facsimile system comprises a carrier which carries a write head and a read head mounted on a belt w hich is moved linearly in both directions by a pulse motor. The read head is composed of the end of a flexible optical fiber assembly having an emission fiber for illuminating a spot on an original paper and a receiving fiber for detecting the reflected brightness of a cell in said illuminated spot. The write head is composed of the end of the other optical fiber one end of which is positioned at the output of a laser beam source, which heats a thermal printing paper selectively through the optical fiber. Thus the thermal printing paper is heated by a laser beam and the color of the paper is selectively changed according to the pattern to be printed.