The present invention provides a display device comprising a display panel and a backlight device comprising a main light guide body which irradiates light toward the display panel. A sub light guide body is arranged on the back surface of the main light guide body is divided in the center by a first air layer. Both end portions of the sub light guide are optically coupled to the main light guide, and a plurality of solid state light emitting elements are arranged in the inside of the air layer of the sub light guide.