A housing of an optical scanning device includes a first abutting portion and a second abutting portion. In the optical scanning device, an optical axis adjustment and a focal position adjustment in a main scanning direction and a sub scanning direction are conducted in a state where a part of a holder that holds a light source unit for emitting multi-beam light abuts on the first abutting portion and in a state where a part of a peripheral edge of an optical element that has both a collimator lens function and a cylindrical lens function abuts on the second abutting portion. Furthermore, a beam pitch of the multi-beam light is adjusted by rotating the holder around an optical axis in a state where the holder abuts on the first abutting portion.