A boiler facility includes a boiler having a combustion chamber in which a burner is installed, a fuel pipe for supplying fuel to the burner, an air duct for supplying air sucked by a blower to the boiler, an oxygen supplier having an oxygen pipe connected to the air duct and a flow rate controller provided in the oxygen pipe, and a control unit. The control unit sets an air amount that is smaller than the reference air amount for burning the fuel, and controls the blower so that the set air amount is supplied to the boiler. Further, the control unit sets an oxygen amount for fuel combustion, and controls the flow rate controller so that the set oxygen amount is supplied to the air duct.