LIGHT SOURCE DEVICE

PROBLEM TO BE SOLVED : To provide a light source device which has a stable and high light-emitting property in spite of its small size. SOLUTION : The light source device comprises a high-pressure mercury discharge lamp formed by arranging a pair of electrodes in a discharge container in which rare gas, halogen, and mercury are enclosed, a concave reflection mirror housing the high-pressure mercury discharge lamp, reflecting the light irradiated therefrom and projecting the reflected light through an opening, and a translucent front glass arranged at an opening of the concave reflection mirror. The concave reflection mirror is composed of a substrate made of metal, an intermediate layer formed on the inner surface of the substrate, and a visible light reflecting layer consisting of a dielectric multilayered film layer fitted on the intermediate layer.