The present invention, main light inlet device for a tunnel according to the invention, has a long duct shape to be provided along the longitudinal direction of the tunnel to the tunnel entrance boundary ceiling portion, the body hollow part formed therein relates to the main light inlet device for the tunnel; Mineral oil inlet formed in the tunnel inlet-side end of the body such that main light from entering the hollow portion; A plurality of halo exit the said main light entering the hollow portion formed in the lower surface of the body to be irradiated to the inside of the road tunnel, located in the lower body; And located respectively between said plurality of halo outlet plurality of reflective portions for reflecting the main light within the hollow portion; including, but the plurality of halo outlet is such that the mineral oil inlet lowered against the bottom surface of said hollow part each of which is formed to have an angle (α) inclined, the plurality of reflection portions are formed to have an angle (β) being each inclined to lower the opposite side of the mineral oil inlet.
According to the present invention, in a longitudinal direction on the lower face of the body halo outlet and the reflection part alternately arranged, and on the halo outlet and being reflective portion provided at an angle such that each lower the opposite side of the mineral oil inlet and mineral oil inlet, the boundary entrance to the tunnel portion in the tunnel entrance side as well as in daylight is irradiated so effectively inside of the inner road can be preferably applied to the entire boundary.