PURPOSE: To enable to surely ignite and to obtain the ignition characteristic, which is stable in service life, by a structure wherein an air chamber and an air port are provided in an ignition heater insulator, on which an ignition heater is held, in order to supply air from the air port through the air chamber to an ignition heater part.

CONSTITUTION: An ignition heater insulator 16 consists in arranging an air chamber 17 on the side, which fits on an outer wick tube, and also arranging an air port communicating to the air chamber 17 and at the same time holding an ignition heater 13. Due to the constitution as mentioned above, the certain fixed amount of air is kept in the air chamber 17 after passing through the air port 18 so as to be mixed with the gas evaporated from a wick 2 by the red heat of the ignition heater 13 in the periphery of the ignition heater 13. Further air is supplied to said air through the air port 18 by the force of updraft produced due to the developed amount of evaporated gas and the temperature of the ignition heater 13. When the air fuel ratio of the resultant gas-and-air mixture reaches a proper value, ignition occurs by the red heat of the ignition heater 13 and a pilot flame 19 shifts to the wick 2, resulting in spreading flame to the wick 2 at large.