A light source device includes: a light source to emit first color light; a fluorescent member having a first region that includes a fluorescent body to convert at least a part of the first color light into second color light different from the first color light when irradiated with the first color light and a second region to transmit the first color light; a wave plate; a reflecting member to reflect the first color light transmitted through the wave plate; and an optical path separating element provided on an optical path between the light source and the fluorescent member and transmit one of the first color light emitted from the light source and reflected light of the first color light by the reflecting member, and reflect another one.