PURPOSE: To make it possible to pick up the sunlight evenly all day long without pursuing the sun by using a prism and a lens to reflect and lead the sunlight in the necessary direction.

CONSTITUTION: A prism plate 5 with one side being a plane and the other side formed in symmetric V-form prisms is placed constantly with the prism grooves 10 in the north and south directions, and the sunlight is picked up from the plane 12. The sunlight B incident to the plane 12 of the prism plate 5 is reflected by the prism plate 5 into B', and the angle in the direction of the optical axis D of a condenser 6 is reduced. The reflected sunlight B' is reflected again by the condenser 6 into the sunlight B" and led to a light leading port 9 through a reflection throat 7. Since the length H of the reflection throat 7 in the optical axis direction is made almost equal to the focal distance of the condenser 6, the sunlight B" makes the image formation at the light leading port 9.