Laser scanning device for scanning light beam and image forming apparatus including the same

In a laser scanning device, a first light shielding portion and a second light shielding portion respectively shield a first light shielding region and a second light shielding region from a light beam. The first light shielding region is a part of a first region which is on one side of a target intermediate region and the second light shielding region is a part of a second region which is on the other side of the target intermediate region. The target intermediate region is a belt-like intermediate region of a light receiving surface of a light sensor. Widths of the first and second light shielding regions in the main scanning direction gradually expand from first and second base end portions to first and second side edges which are opposite ends of the light receiving surface in the sub scanning direction.