Disclosed are a lamp device (14) and a semiconductor light-emitting element (38a). The lamp device (14) is provided with a frame (20) having a heat conductive section (28d); this heat conductive section (28d) is thermally connected with an external heat-radiating body. The heat generated by the semiconductor light-emitting element (38a) is thermally conducted to the heat-radiating body through the heat conductive section (28d). A heat-sensitive element (54) is thermally connected with the heat conductive section (28d). In the lamp device (14), there is provided an ignition circuit (23) that ignites the semiconductor light-emitting element (38a); this ignition circuit (23) controls the output of the semiconductor light-emitting element (38a) in accordance with the temperature detected by the heat-sensitive element (54).