A process for producing metallic iron from a charge stock mixture containing a carbonaceous reducing agent and an iron-oxide-containing substance, characterized by including the steps of determining, corresponding to a preselected target carbon concentration in metallic iron, a target formation temperature of an initial molten slag first formed in the charge stock mixture by heating the charge stock mixture, the initial molten slag containing gangue components, unreduced iron oxide and ash of the reducing agent; preparing the charge stock mixture for forming of the composition of the initial molten slag corresponding to the target formation temperature; and heating the charge stock mixture to thereby accomplish not only reduction/melting of the charge stock mixture but also forming of theinitial molten slag. The metallic iron having the target carbon concentration can be efficiently produced by this process.