Disclosed is a light scanning unit that includes an imaging optical system disposed between a beam deflector and a surface to be scanned. The imaging optical system includes two adjacent imaging optical devices that are inclined with respect to the light path. The inclination directions of the two adjacent imaging optical devices may be determined according to the number of reflection units that are disposed on the light path between the two adjacent imaging optical devices. The disclosed light scanning unit of the above configuration may advantageously exhibit reduced ghost images, reduced bowing of the scan line, improved beam diameter uniformity, and/or improved color registration.