To provide a miniaturized lighting device that emits light appropriate for illumination of a display system and a projection type display system including the lighting device. A lighting device includes solid-state light sources to emit light, light introducing elements to equalize an illumination distribution of the light emitted from the solid-state light sources, and reflection type polarizing elements into which the light emitted from the solid-state light sources is introduced. The lighting device is characterized in that the reflection type polarizing elements are disposed inside the light introducing elements or on light exit end faces of the light introducing elements, and that the solid-state light sources reflect the light which has been reflected by the reflection type polarizing elements.