At the same time to effectively the generation of scaffolds of the lump-shaped metal material layer protection, and even If the molten metal occurs, providing manufacturing apparatus that can solve the scaffold certainly. Stationary non isomorphic the raw material charging chute (4, 4) the filling layer forming material (A) and the lump-like metal material (B) for from the arc width direction of the both end portions (2, 2) as to a charged in that order, and the central portion in the width direction of the electrode (5) towards the bottom after the formation of the raw material charge layer 12 and the lump-like metal material layer 13 on the inclined surface having a downward slope, lump to arc heating of the electrode 5, the shape a metal material layer 13, the lower end at the same time for producing molten iron by progressive melting, while thus lowering the lump-like metal material layer 13, the raw material charge layer 12, the inclined surface, the secondary combustion burners 6 in the ceiling (1) with an oxygen-containing gas (C), a blown from the configuration lump-shaped metal material by burning a CO containing gas generated from the layer 13, to heat a lump-like metal material layer 13 by its radiant heat, and the molten slag layer in the above the (15), also, like in the lump in the lower side than the surface of the metal material layer (13), providing a shock generator (18).