A daylighting device according to an aspect of the invention includes at least a daylighting film that includes a base having optical transparency and daylighting portions having optical transparency and provided on one surface of the base. Each of the daylighting portions has a reflective surface by which light incident on the daylighting portion is reflected and the light reflected by the reflective surface and output from a second surface of the base has a characteristic that the light travels toward a space on a side where the light is incident on the reflective surface, the space being one of two spaces divided by a virtual plane as a boundary which is vertical to the second surface of the first substrate and parallel to a direction of the daylighting portion extending, and intervals s between adjacent daylighting portions are set to various values.