The present disclosure provides a burner for a reduction reactor, the reduction reactor has a reaction space formed therein, wherein each burner has a fuel feeding hole and multiple oxygen feeding holes formed therein, wherein each burner has an elongate combustion space formed at one end of a head portion thereof, the combustion space fluid-communicating with the reaction space of the reactor, wherein the elongate combustion space has a length such that oxygen supplied from the oxygen feeding holes thereto is completely consumed via oxidation or combustion with fuels supplied from the fuel feeding hole thereto only in the elongate combustion space upon igniting the burner.