PURPOSE: To save electric power by providing sun light collecting means on the outside of a tunnel, guiding the collected sun light into the tunnel entrance with optical fibers, and radiating the sun light of the optical fibers into the tunnel.

CONSTITUTION: Basic illumination lighting fixtures 2 and entrance illumination lighting fixtures 3 are arranged respectively on both side walls in a tunnel portion 1. Sun light collecting means 4 are installed on the outside of the tunnel 1, and light receiving terminals of the optical fibers 10 are fitted at light collecting focal point positions of light collecting Fresnel lenses 8 so that the maximum light received quantity can be automatically obtained by photo- sensors. The optical fibers 10 transfer the light collected by the sun light collecting means 4 to the entrance illumination lighting fixtures 3 with high efficiency, and radiating terminals 9 used for the sun light collecting means 4 of the optical fibers 10 are used as light sources for the entrance illumination lighting fixtures 3.