PURPOSE: To simultaneously attain the increase of a reduction speed and the increase of a heat supply rate to a reaction system by specifying the quantity of the oxygen to be blown through respective tuyeres in an ore melting period and an oxide recovering period.

CONSTITUTION: The reduction speed is first increased by simultaneously blowing carbonaceous powder and oxygen into a slag layer 3 in a stage for melting and reducing the ore by blowing oxygen while charging ore, carbonaceous material and oxygen into the furnace. The quantity of the oxygen to be blown at this time is specified to the quantity at which the carbonaceous material powder is completely burned, i.e., 0.1W1.0 times the theoretical quantity Q of the oxygen to be burned defined by the equation. In the equation, C, H, O%: the elementary analysis value of coal, Wcoal; the blowing rate kg/h of the carbonaceous material powder from tuyeres 6 in the slag layer. The quantity of the oxygen to be blown into the slag layer is specified to 0.1W0.7 times the theoretical quantity Q of the oxygen to be burned defined by the equation in the stage for blowing the oxygen and reducing and recovering the oxide in slag while charging only the carbonaceous material and the flux after the completion of charging of the ore.