PURPOSE: To obtain the visual monitor of equal magnification by facing the other ends of 2n-pieces of optical fibers to n-pieces of photoelectric converting elements alternately and by arranging the ends of the rest of said n-pieces of fibers in a dark box provided with peep windows arranged in the same intervals as the reading ends.

CONSTITUTION: A line of thirty-two optical fibers 32 is held by two groups of light emitting diodes 33a and 33b and is fixed by a black mold 34. As for other ends of the optical fibers 32, by every two fibers, i.e. sixteen fibers are put together into one group. The sixteen fibers 32a are fixed corresponding to sixteen phototransistors or photodiodes 35. The photoelectric converting element 35 receives the reflected light of a spot region having a diameter approx. twice the diameter of the optical fiber on a surface of the paper and reads it as electric signals. The rest of the optical fibers 32b of sixteen are fixed in a line in the same intervals as the reading-side ends by a black mold and are covered with a dark box 36 to enable visuallizatin of the ends through the windows 38.