A projecting direction control system for a vehicle lighting device is provided with height detecting means for detecting variation in the height of a front-wheel or a rear-wheel axle portion, auxiliary detection means for accurately controlling the direction of an optical axis of projection light for a vehicle headlamp in response to vehicle load variation, and light projection control means for controlling the optical axis of light in response to variation in the vehicle posture according to the information obtained by the height detecting means and the auxiliary detection means. When the auxiliary detection means such as a seat sensor becomes in abnormal condition, the direction of the optical axis of light is controlled so as to be tilted downward from the direction of the optical axis of projection light with the auxiliary detection means remaining in a normal condition.