A light source device includes: a light emitting element; a heat slinger including a first surface in contact with the light emitting element and a second surface opposite to the first surface; a thermoelectric element including a heat absorbing surface in contact with the second surface and a heat radiating surface opposite to the heat absorbing surface, the thermoelectric element producing a temperature difference upon having current flowing in the thermoelectric element; a heat sink in contact with the heat radiating surface; a frame body that is open in a stacking direction of the light emitting element, the heat slinger, the thermoelectric element, and the heat sink, and supports the light emitting element, the heat slinger, the thermoelectric element, and the heat sink in a stacked state; and a sealing member that is filled in the frame body to cover the heat slinger and the thermoelectric element.