PURPOSE: To produce steel from iron ore with high thermal efficiency, by melting the reduced iron produced from iron ore in a calcining furnace in a melting furnace in the state of high temp. and further supplying the same in a molten state into a steel making furnace.

CONSTITUTION: Iron ore and carboneous materials as reducing agents are supplied into a calciming furnace 1 such as a rotary kiln whereby reduced iron is produced. The reduced iron enters the inside of a hood 2 together with the char formed with the residual parts of the carboneous materials which are reducing agents. In said hood, the reduced iron is once held of temp. and is stored; thereafter, the reduced iron is supplied by each specified volume into an induction electric furnace 5 by opening and closing of the bell of a chuting spout 3. The reduced iron reacts with the char in the furnace 5 and absorbs the carbon thereof to form pig iron of a low m.p. which is melted at low temp. The molten pig iron is transferred by a ladle 7 into the next steel making state, by which the pig iron is refined to steel. Since the iron is treated with high thermal efficiency throughout the entire stage, the cost of steel making is reduced.