An optical scanning device includes a third fθ lens, an adjusting bar, a pressing portion, a columnar member, and a movement restraining section. The adjusting bar is disposed parallel with a longitudinal direction of the third fθ lens and has projections which are capable of pressing against the third fθ lens at plural points in the longitudinal direction of the third fθ lens. The pressing portion and the columnar member press the adjusting bar against the third fθ lens. The movement restraining section is configured to set the pressing portion and the columnar member in a first state in which the pressing portion and the columnar member are movable in a direction parallel with the longitudinal direction of the third fθ lens or in a second state in which the pressing portion and the columnar member are restrained from moving.