PURPOSE: To stabilize the quality of a cast iron which is different in the chemical components contained therein by adjusting part of the molten metal in a fore hearth with a heating furnace for adjustment supplying the same together with the molten metal from the fore hearth into a ladle at the time of producing the cast iron having the chemical components different from the chemical components of the molten metal itself.

CONSTITUTION: The melt of the cast iron contg. the predetermined chemical components is once accumulated from a cupola 1 into the fore hearth 2 and is transferred from the fore hearth 2 into the ladle 3, from which the molten metal is poured into respective molds 6 of a casting line 5. Part of the molten metal from the fore hearth 2 is conducted to the heating furnace 4 for adjustment and the material to be added is added to such molten metal and is held at a prescribed temp. to melt at the time of adding another metallic element or the like further to the chemical components of the molten metal itself. The molten metal adjusted in the above-mentioned manner is mixed with the molten metal charged from the fore hearth 2 into the ladle 3 in the ladle 3. The above- mentioned additive material is thereby uniformly dispersed into the molten metal and the generation of segregation in the mold 6 is obviated.