ELECTRODELESS ELECTRIC DISCHARGE LAMP AND ELECTRODELESS ELECTRIC DISCHARGE LAMP DEVICE

PROBLEM TO BE SOLVED: To provide an electrodeless electric discharge lamp and an electrodeless electric discharge lamp device superior in ambient temperature property at a low temperature and capable of achieving stable output. SOLUTION: This electrodeless electric discharge lamp is equipped with an arc tube wherein mercury and rear gas are enclosed in a glass bulb constituted by a light emitting part, a neck part connected to the light emitting part, and a stem sealed onto the neck part and having a thin tube wherein amalgam is enclosed; and a base provided on an end of the emitting body so as to cover the sealing part of the neck part and the stem. A high frequency current is supplied to an induction coil installed on an outside of the arc tube by a high frequency power source so that the inside of the arc tube is excited and emitted. A heat retaining member is provided on a part which is considered that a temperature at lightening is the lowest on the outer surface of the arc tube. The heat retaining member is provided so as to cover the glass bulb in a range of 1/5 to 1/3 of the whole length of the glass bulb from the base to a tip of the arc tube.