An apparatus for manufacturing molten iron includes: an iron ore-mixing/pre-reducing furnace receiving and mixing natural iron ore and oxidized iron ore to form a mixture, and heating or pre-reducing the mixture using a reaction gas to form a pre-heated or pre-reduced iron ore; an iron ore reduction furnace receiving the pre-heated or pre-reduced iron ore iron ore and reducing the pre-heated or pre-reduced iron ore using a reduction gas to form a reduced iron ore and produce the reaction gas; a molten gasification furnace receiving coal and the reduced iron ore and producing molten iron and the reduction gas; and an iron ore oxidizing-burning furnace receiving part of the reduced iron ore discharged from the iron ore reduction furnace and oxidizing the received reduced iron ore to produce the oxidized iron ore. The oxidized iron ore is supplied to the iron ore-mixing/pre-reducing furnace.