A light source device includes a plurality of light source units, a plurality of first heat processing units, a second heat processing unit, a plurality of thermal connectors, a light processing unit, and a plurality of optical connectors. The plurality of thermal connectors make the plurality of first heat processing units and the second heat processing unit attachable to and detachable from each other, and thermally connect the plurality of first heat processing units and the second heat processing unit. The light processing unit processes the light output from the plurality of light source units. The plurality of optical connectors make the plurality of light source units and the light processing unit attachable to and detachable from each other, and optically connect the plurality of light source units and the light processing unit.