A light source device includes a semiconductor light-emitting element; an optical element including lens regions that change an intensity distribution of light emitted from the semiconductor light-emitting element; and a phosphor element that emits, as excitation light, the light with the intensity distribution changed by the optical element. Respective focal points of the lens regions are present in front of or behind a light-emitting surface of the phosphor element in different positions. At least one of the lens regions is astigmatic. An excitation beam from the at least one of the lens regions with the astigmatism forms a circle of least confusion near an associated one of the focal points, and a first focal line and a second focal line sandwiching the circle behind and in front of the circle, respectively. Beams from the lens regions overlap each other on the light-emitting surface of the phosphor element.