Light source unit and projection display device applied with the light source unit

To secure uniformity in in-plane luminance of light emitted from a semiconductor light emitting device array. A light source unit 10A is provided with a semiconductor light emitting device array 13 wherein a plurality of semiconductor light emitting devices 13R, 13G, 13B are arrayed on a substrate 12 in a two-dimensional manner, a condenser lens 14 for condensing light emitted from the semiconductor light emitting device array 13, and a light guide 11 in which mirror surfaces 11am, 11bm, 11cm are formed along with an inner wall surface from a light incidence port to a light emission port, the semiconductor light emitting device array 13 and the condenser lens 14 are disposed in order toward the light emission port internally on the side of the light incidence port, for emitting the light condensed by the condenser lens 14 from the light emission port while narrowing down a part of the inner wall surface approximately along with a condensing angle theta1 of the condenser lens 14.