To effectively providing natural light even inside a building or to such building as no sufficient natural light is acquired, while the interior of building is concealed and unwanted people is prevented from entering from outside the building, and only a damaged part is replaced if a glass, etc., is damaged.

There are provided a translucent columnar structure body 2 whose cross-sectional surface is polygonal, a frame 3 to which a plurality of columnar structure bodies 2 are detachably fitted side by side for free rotation around a center axis in the lengthwise direction, and a rotation mechanism 4 which integrally rotates the plurality of columnar structure bodies 2 at a prescribed angle.