To provide an oxygen supplying method with which the heat energy can effectively be utilized by improving a secondary combustion ratio when iron scrap is melted in a vertical melting furnace.

The oxygen for primary combustion is supplied from primary blasting tuyeres disposed at the lower part of the vertical melting furnace, and the oxygen for secondary combustion is supplied from secondary blasting tuyeres disposed at the upper part of the primary blasting tuyeres while maintaining the supplying speed of the oxygen for secondary combustion in the suitable range.