PURPOSE: To raise the temperature of fuel up to the vaporizing temperature for providing a fast start-up of vaporizing combustion by a method wherein a part of a fuel supply pipe through which liquid fuel is supplied to a burner is composed of a heat-generating pipe which generates heat as it is energized.

CONSTITUTION: A part of a fuel supply pipe 3 through which liquid fuel is supplied to a burner 1 is composed of a heat-generating pipe 3a which generates heat as it is energized, and the heat-generating pipe 3a is located at a position where it is heated by the combustion heat of the burner 1, so that the heat- generating pipe 3a is also heated by the combustion heat of the burner 1. When energized, the heat-generating pipe 3a itself generates heat and reaches a temperature enough to vaporize kerosene as the liquid fuel. Therefore, when a magnetic pump 5 is put in operation to send the fuel into the heat-generating pipe 3a, the fuel is immediately vaporized in the heat-generating pipe 3a, and blown toward a venturi pipe 8 of the burner 1 through a nozzle 7. Air is induced by blowing of the fuel and mixed with the fuel in a mixing chamber, and the mixture is sent to a burner port. Then, when the mixture is ignited, the fuel burns in a gasified state. Once combustion starts, the heat-generating pipe 3a is heated by the combustion heat.