PURPOSE: To enable the starting without elevating the starting voltage even when it is every cold by providing a heater comprising a heating film and thermistor with positive characteristic on the tube wall surface to heat upto a specific temperature when a gas temperature is lower than the specific temperature on starting.

CONSTITUTION: The lamp is provided with a tube 2 coated with a fluorescent coating 1, heating film 10 formed on the wall surface of the tube 2 by staining or evaporation, and thermal sensor 11 connected to an electrode pin 3 provided on a cap 4. The thermal sensor 11 is connected to a heater electrode pin 3a and provided in the inside of the tube 2, and constituted with a thermistor 11a, silver paste 11b contacting with the heating film 10, and an evaporated silver layer 11c adjacent to the electrode. Thus the lamp can be started without elevating the starting voltage even in a very cold atmosphere.