To eliminate a lower temp. zone with the developing position changed in an early stage by measuring the temp. distribution in a furnace hearth with plural temp. sensors in the furnace hearth refractor, estimating an existing position of the low temp. zone in the furnace, controlling gas blowing quantity from tuyeres on the furnace hearth, forming molten metal stream from the high temp. zone to the low temp. zone and promoting the melting.

At the time of melting raw material of scrap, etc., charged in an electric furnace, the gas is blown into the molten metal 1 in the furnace form the tuyeres 7 for gas blowing arranged in the furnace hearth 13 and the melting and refining reaction of the charged mateal in the furnace are promoted by utilizing this stirring force of the gas. At this time, the temp. distribution in the furnace hearth is measured with plural temp. sensors 10 embedded into the furnace hearth refractory 3 and the existing position of the low temp. zone in the furnace caused by remaining the unmelting scrap is estimated from the temp. distribution in the furnace hearth. Based on the estimated position, the gas blowing quantity from the tuyeres 7 is controlled through a gas flow rate control device 11 so as to flow the molten metal 1 from the high temp. zone to the low temp. zone, and promote the melting of scrap.