To provide an optical write-in apparatus which enables to keep optical write-in operation and to reduce down time of a machine, and to provide a digital copying machine.

The optical write-in apparatus which scans in a main scanning direction with a semiconductor laser driving means which drives a semiconductor laser and a deflection means which deflects a light beam, includes: a light intensity detection means which detects the light intensity of the semiconductor laser; a comparing and calculating means which compares and calculates a driving current generated by the light intensity detected by the light intensity detection means and the semiconductor laser driving means; a using range determining means which determines the using range of the light intensity and the driving current of the semiconductor laser on the basis of the compared and calculated result calculated by the comparing and calculating means. The using range determining means controls the semiconductor laser in the using range of the semiconductor laser on the basis of the decided result of the using range.