An automatic light system is provided for automatically turning on and off vehicle lights in accordance with the surrounding environment. The system includes an imaging device that images an area in front of the vehicle and generates image data; an image processing unit that generates light mode information on the basis of the brightness in an upper region and lower region of the image data; and a light control unit that controls the lights on the basis of the light mode information. The image processing unit sets a higher weight to a measurement region in the movement direction of the vehicle from among a plurality of measurement regions set in the upper region and a lower weight to the other measurement regions to calculate the brightness in the upper region and generates the light mode information on the basis of the brightness in the upper region.