To enable a utilization of exhaust gas for efficiently preheating scrap by disposing a plurality of preheating vessels above a furnace lid of a melting furnace substantially on the same plane for heating scrap using the exhaust gas discharged from the melting furnace and sequentially moving a plurality of these vessels between a scrap charging position and a scrap preheating position.

When melting is started by generating an arc between a scrap 15 which is charged into a melting furnace 16 and electrically connected with a furnace bottom electrode 14 and an upper electrode 4, a scrap 11 in a preheating vessel 1 is held by a scrap supply door 6 and is preheated by an exhaust gas of a high temperature generated at the time of melting the scrap 15. During such an operation, a new scrap 23 is charged into a preheating vessel 3 by means of a conveyor 22. When the scrap level is lowered corresponding to the progress of melting of scrap in the melting furnace 16, the scrap supply door 6 of the preheating vessel 1 is opened so as to supply the preheated scrap 11 into the melting furnace 16. Subsequently, upper and lower slide sleeves 10, 8 are separated from the preheating vessel 1 and the preheating vessel 3 is moved to a preheating position.