PURPOSE: To obtain a burner having high energy saving effect, by holding excessive air enriched with oxygen to be supplied to the burner in a holder temporarily.

CONSTITUTION: A flow control valve 15 for adjustment of a temperature to the profixed one of a burner 7 by control of an air flow to the burner 7 is provided in a duct 6 between a blower 3 and the burner 7. Air enriched with oxygen from the duct 6 is supplied to the burner 7 from a flow control valve 16 through the flow control valve 15 and is supplied to a holder 21 from valves 17 and 18 through ducts 19 and 20. The holder 21 possesses a capform casing 22 which is water tight and is capable of moving up and down. With this, the burner having high energy saving effect can be obtained, as a flow of the air enriched with oxygen can be increased according to a load when the load of the burner is varied drastically.