In a light control device for a vehicle, a control portion determines whether an illuminance detected by an illuminance sensor reaches a first reference illuminance, and performs a turning on or off control of lights of the vehicle based on the determined result. When the control portion receives an external environment change signal from an environment change detecting means, the control portion uses a second reference illuminance higher than the first reference illuminance, instead of the first reference illuminance, and performs the turning on or off control when the illuminance detected by the illuminance sensor reaches the second reference illuminance. Accordingly, vehicle lights can be suitably turned on or off in accordance with an external environment of the vehicle.