Abstract: A metal vapor discharge lamp comprising a FEC. a semiconductor switch and a thermal response switch and operated at a supply voltage of 100 to 130 V. The thickness if the FEC is 0.45 to 0.8 mm and the breakover voltage of the semiconductor switch is 60 to 100 V so that the discharge is safely caused in a light emitting tube and lighting at a voltage of -10% of the rated voltage is enabled. The open time of the thermal response switch is not less than 30 seconds so that starting is ensured even when the dimension of the light emitting tube is long or the pressure of xenon is high.