A light control system acquires presence information that indicates whether or not another vehicle is present in a lateral or rear direction relative to an own vehicle. If presence information indicates the presence of another vehicle, the illumination range of the headlights of the vehicle is changed so as to be narrower. Thus, when another vehicle enters the illumination range from a lateral direction relative to the vehicle equipped with the system, the illumination range of the lights of the vehicle is changed to a narrower range before the entry into the illumination range.