a lens that emits, as projection light, natural light incident from half of the celestial sphere;

a sensor that photoelectrically converts the projection light projected onto a light receiving surface, and outputs the photoelectrically converted projection light; and

a determination circuit that determines the presence or absence of sunshine on the basis of an output of the sensor,

wherein the sensor has a plurality of detection areas on the light receiving surface, and is configured to output a signal corresponding to an intensity of the projection light incident on each of the detection areas, and

the determination circuit removes a scattered light component included in the projection light on the basis of a difference operation of the signal output from each of the detection areas to extract only a direct light component to be included in the projection light at the time of incidence of sunlight, thereby determining the presence or absence of sunshine in the natural light.