Refining method of molten iron and reduction smelting method for producing molten iron

This invention provides a method of smelting a low carbon molten iron comprising the steps of executing desulfurization treatment by supplying a desulfurizer to a molten iron and stirring the molten iron; heating or carburizing the molten iron before or after the desulfurization treatment; and executing decarburization treatment of the molten iron after the desulfurization treatment in a decarbonization furnace. The molten iron is produced by charging an ore reduced to metallization into a melting/reducing furnace. Dust coke, oil coke and waste plastics can be used as the carbon material. A sintered ore having a small particle size can be used as an iron source.