A daylighting system includes: a functional film which transmits light from an outdoor area of a building to introduce the light to an indoor area of the building; a weather detection unit configured to detect weather in a location at which the functional film is installed; and a control unit configured to control a transmittance of the functional film, based on a result of detection by the weather detection unit. The weather detection unit is configured to detect the weather, based on a result of comparing an illuminance of the light from the outdoor area with a reference value for the illuminance, and a result of comparing a color temperature of the light from the outdoor area with a reference value for the color temperature.