An optical scanning device includes a light source that emits a light beam, an optical deflector at which a light beam emitted from the light source is incident, the optical deflector deflecting the incident light beam, an optical system that guides the deflected light beam to surface to be scanned by the deflected light beam, a driving device that drives at least a portion of the optical deflector, a thermal storage member mounted on the driving device, the thermal storage member absorbing and storing heat generated by the driving device, thereby controlling a temperature gradient of the driving device, and a casing body that accommodates the light source, the optical deflector, the optical system, the driving device, and the thermal storage member.