A backlighting device for producing a uniform luminance throughout a screen for use in LCD devices includes a semicylindrical concave surface on a light-transmitting top face of a light-guiding plate, lamps installed near two opposed edges of the light-guiding plate, a light-diffusing plate on the top side of the light-guiding plate, a light-reflecting plate attached to the bottom face of the light-guiding plate, and reflecting film patterns between the light-guiding plate and the reflecting plate. The present invention provides for a simpler manufacture of the backlighting devices producing a high and uniform luminance.