A light source device includes an excitation light source which generates excitation light, a fluorescent member containing a fluorescent substance which absorbs the excitation light to generate fluorescence, an emitting side optical member which is provided on an emitting end face of the fluorescent member, and a reflector which is provided on the side surface of the fluorescent member. The reflector has an optical property of reflecting the excitation light and the fluorescence. The emitting side optical member has an optical property of reflecting the excitation light and transmitting the fluorescence.