Provided is a novel control technology for a light device for a vehicle. The control device starts an alighting illumination process after a vehicle stops so as to ensure the driver's field of view when alighting the vehicle. When the alighting illumination process is started, the control device stands by until the driver alights the vehicle (S110). When the driver alights the vehicle, it is determined whether the vehicle is in the premises of the driver's home, and whether it is nighttime (S120, S130). If the determinations are both affirmative (Yes in S130), a lighting control process is started (S140). In the lighting control process, an area forward of the driver as he or she advances is illuminated with a head lamp while the range of irradiation of light by the head lamp is switched in accordance with the movement of the driver, until the driver enters the home or continuously stays out of the field of view of an external camera.