PURPOSE: To enable a gas/catalyst combustion device to be applied in a heater or a heating clothes by a method wherein the gas/catalyst combustion device stores a combustion catalyst, has a thermal conductive combustion chamber, an opening hole at a recessed part of a thermal driving pump heating part is disposed to direct upwardly under its practical use and a working liquid circulation closed circuit is provided.

CONSTITUTION: As gas in a gas cylinder 17 is injected out of a gas injection nozzle 26, surrounding air is sucked through an ejector 28 to form mixture gas, the mixture gas is ignited through a combustion catalyst 29 at a combustion chamber 2 of the gas/catalyst combustion device and then a heating part 3 of a thermal driving pump 1 is heated. Bubbles of working liquid generated at a recessed part 4 for heating liquid are grown toward a gas/liquid exchanging chamber 7, close a suction side check valve 8, open a discharging check valve 9 and then the warmed working liquid corresponding to a volume of vapor bubbles is circulated through an external heated item 12. The vapor bubbles are condensed within the gas/liquid exchanging chamber 7 and the working liquid is fed from a feeding tank 14 into the thermal driving pump 1 through the suction side check valve 8. With such an arrangement as above, effect can be realized in heating and warming of clothes and the like.