A light source device according to the present disclosure includes a first light source configured to emit a first light flux, a second light source configured to emit a second light flux, a third light source configured to emit a third light flux, a first light combiner configured to enlarge a first light flux width of the first light flux, and combine the first light flux and the second light flux to generate a first combined light flux, and a second light combiner configured to combine the first combined light flux and the third light flux with each other to generate a second combined light flux. The first light flux width is equal to a second light flux width of the second light flux or smaller than the second light flux width, and the first light flux width is smaller than a third light flux width.