A light source device is disclosed. An embodiment of the light source device includes: an excitation light source configured to emit irradiation light of a color component to be used as excitation light and projection light; a fluorescent member disposed in an excitation light path and configured to generate fluorescence of a color component different from the color component of the irradiation light when being irradiated with the irradiation light; a light path merger unit configured to merge a fluorescence light path through which the fluorescence generated with irradiation of the irradiation light is delivered, and a projection light path through which the projection light is delivered; and a light path switch disk configured to switch the irradiation light between the excitation light path and the projection light path.