To provide a light source device with further downsizing aimed at and capable of restraining deterioration of luminance or life of a light-emitting element caused by heat generated at the light-emitting element.

The light source device 110 is provided with an LED 10 as a light-emitting element emitting light of a predetermined wavelength region, a support substrate 20 supporting the LED 10, and a heat sink 30 arranged on an opposite face from a side with the LED 10 arranged on the support substrate 20 and having a plurality of fins 32 protruding toward a side with the LED 10 arranged.