A light source device capable of improve energy efficiency is provided. A light source device includes a yellow phosphor that emits yellow fluorescence excited by exciting light, a red laser light source that emits red laser light, a first light combining unit that generates first composite light by combining the emitted yellow fluorescence with the emitted red laser light, a blue laser light source that emits blue laser light, and a second light combining unit that generates second composite light by combining the combined first composite light with the emitted blue laser light.