Abstract: In a lamp main body in a discharge lamp provided in a lighting apparatus of an edge-lighting type which is used as a back-lighting section of a liquid crystal display apparatus, refractive indexes are distributed such that a light emitted from an inner space traveling in the lamp main body can be guided to a specific direction. In other words, the lamp main body is divided into a plurality of portions and the portions are formed such that refractive indexes become gradually smaller from a light converging side towards a back surface side which is opposite to the light converging side. With this arrangement, a discharge lamp, which is capable of emitting a light from a surface of the lamp main body to a specific direction, can be obtained. Moreover, when the discharge lamp is used, efficiency of utilization of a light is improved, thereby making it possible to obtain a lighting apparatus with high surface brightness and low power consumption.