A light source device (2) comprises: a LED unit(light emitting element unit) (3) including a unit body (30) equipped with a FPC (light emitting module) (37) which includes a LED (semiconductor light emitting element) (31); and a base (4) equipped with a connector (42) for supplying the LED (31) with power from an external light source. The unit body (30) is formed of a material having higher heat conductivity than the base (4), and the base (4) is formed of an insulating material. When the LED unit (3) and the base (4) are integrally configured, a connector electrode (43) is electrically connected to a power supply pad (39) of the FPC (37) to allow for power supply to the LED (31).