PURPOSE: To eliminate an extra heating device for generating steam, by utilizing the combustion heat of an automobile engine as a heat source.

CONSTITUTION: A nozzle 15 having a steam discharge port 16 is connected with a water tank 1 and heat exchanger 11 by means of a connecting tube 18. The heat exchanger 11, made of metal or heat resisting synthetic resin and composed of flat plates equipped with water piping 13 or flexible piping, is fitted detachable to a heat source such as an engine or radiator. The discharge port 16 is open inside the vehicle. Water is stored in a tank. A valve is opened to heat the water in the heat exchanger 11 by virtue of combustion heat of the engine and steam is injected through the nozzle port 16 into the interior space.