A daylighting slat (4) includes: a daylighting plate (51); and a support member (24) that supports the daylighting plate (51), in which the daylighting plate (51) includes; a base that has light transparency; and a plurality of daylighting parts that are provided on a first surface of the base, have light transparency, and form a gap portion between the plurality of daylighting parts, in which a part of a side surface of a daylighting part, which is in contact with the gap portion, functions as a reflecting surface that reflects light entering the daylighting part, and the support member (24), at least a part of which has light transparency, includes a gripping portion (25) that grips at least a part of a peripheral part of the daylighting plate (51) and has light absorbability, and a protective plate (26) formed of a plate body that is provided so as to face a first surface or a second surface of the daylighting plate (51).