An optical scanning device includes a light source having plural light emitting portions, a deflection unit that deflects and scans plural light beams emitted from the light source in a main scanning direction, and plural optical element groups disposed between the light source and the deflection unit and including an optical element having a negative refractive power along a sub-scanning direction intersecting the main scanning direction. An interval in the sub-scanning direction of the plural light beams is adjusted by tilting the optical element having the negative refractive power on an axis along the main scanning direction.