To suppress the occurrence of the phenomenon that a light beam reflected on the surface of a scanning lens 5a returns to a polygon mirror 4a while suppressing an increase in cost.
A scanning optical apparatus 1 has: a semiconductor laser 2a which emits a luminous flux; a deflection scanning unit 4 which deflects and scans the luminous flux with a polygon mirror 4a; and a scanning lens 5a which focuses the luminous flux deflected and scanned with the deflection scanning unit 4 on a photoreceptor drum 51, and these units are mounted on an apparatus frame body 1a. The scanning optical apparatus 1 is characterized in that the deflection scanning unit 4 includes a shielding plate 41 on a motor substrate 4c so as to be unitized with the substrate 4c, the shielding plate 41 shielding the light reflected from the scanning lens 5a.
Kosuke Tobita
Sorimachi Yukiyoshi