PURPOSE: To reduce the cost and to improve the performance, by using a bimorph or an optical galvanometer as a deflector, and controlling the deflector with the detected output of a position detector of an optical beam.

CONSTITUTION: Deflectors 13a, 13b using the bimorph attached with a reflecting mirror are used, and the deflector 13a is utilized to deflect the beam toward the X axis of a photoreceptor 14 and the deflector 13b is utilized to deflect the beam toward the Y axis respectively. Further, an optical sensor 15 is arranged in parallel with the photoreceptor 14 and the write is performed while shifting one laser light toward the X axis of the photoreceptor 14. In case other than the write, since the beam is positioned on the position detecting sensor 15, the mode is switched to the position detection.