An optical scanning device includes a lens having a negative optical power at least in a sub-scanning direction and a lens having a positive optical power at least in the sub-scanning direction between a light source and a deflecting unit. The optical scanning device further includes a coupling lens and an adjusting lens whose positions can be adjusted in an optical axis direction and then bonded with ultraviolet curing resin. Therefore, the magnification of an optical system can be adjusted and consequently a desired scan-line interval can be obtained.