PURPOSE: To utilize light power effectively with simple constitution by rotating or oscillating a light source itself and thus varying the direction of a light beam from the light source.

CONSTITUTION: A driving signal for an alternately reversal rovolution driving shaft is supplied from a motor driving circuit 6 to a driving part 1. Consequently, a light source 3 itself, fitted to a case 2, is oscillated as shown by arrows (a) and (b) direction through the case 2 coupled with the driving shaft to allow a light beam, emitted through a lens 4, to scan on a photosensitive drum 7 horizontally.The power source circuit 5 for the light source 3 supplies a signal for the on-off modulation of the light source according to recording information.