According to the present invention is directed to a second lens mounting structure of the solar light collecting unit, the Fresnel solar light collecting unit to generate electricity by using the solar light collected by the lens, the Fresnel lens with a predetermined height and spacing for damping maintained while above the solar cell facing the Fresnel lens to refract the sunlight condensing from a Fresnel lens and simultaneously uniformly incident on the solar cell surface of the heat generated by the light collecting Fresnel lens to the primary 2 primary lens and additional seating, the second lens unit the? bottom is opened as soon the upper end surface facing the Fresnel lens, with the inside-installed in the cylindrical pipe and the cylindrical pipe a hollow with me convexly protruding Fresnel lens to a spherical lens, a screw, a circumferential outward of the cylindrical pipe from the lower end outer peripheral surface of the cylindrical pipe passing through the cylindrical pipe and a spherical lens coupling the cylindrical pipe with the spherical lens for a solar evenly distributed to the solar cell surface pass through extends through from the annular bracket, and the open lower end of the cylindrical pipe to see one end facing the spherical lens is projected by a predetermined length in the inner direction of the cylindrical pipe, the spherical lens with as soon projecting solar direction from the bottom of the ring-shaped bracket can be made in a predetermined and prevent the come out of the solar cell and the spherical lens height intervals from two to six projecting jaws of spaced. The second lens fitting structure of the solar light collecting device according to the invention made of such a construction is to have any one of the second lens section and matdaeeung of any one of the Fresnel lens collects solar concentrates parts secondary lens, wherein the second lens unit so that the solar cell is passed through the Fresnel lens can be uniformly distributed on the second lens section and the solar cells matdaeeung. In addition, the second lens unit can be radiated by the heat generated by the light collecting Fresnel lens to the primary enemy minimize heat that may be generated in the solar cell and consequently improve the power generation efficiency of the solar cell.