Method of reactor iron making without using electric power in the reactor. Iron scrap and a solid non-petroleum carbonaceous material, i.e., powdery coal or coke, are continuously charged from above into molten iron in the reactor with a space over the molten iron. The carbonaceous material is charged by injecting it with a stream of nitrogen or air. Oxygen gas is simultaneously blown into molten iron below its surface so as to stir it and oxidize the carbonaceous material mainly to CO and blown into the space over the iron to oxidize the CO to CO.sub.2. The amount of oxygen is increased as the amount of molten iron increases. The iron scrap melts from the heat generated by the oxidation. The high temperature exhaust gas is used to preheat scrap to be charged. When the amount of molten iron reaches a predetermined level, it is tapped off until a lower predetermined level is reached. The above steps are repeated. Twin reactor iron making can use the method. Only part of the CO produced in one reactor is oxidized and high temperature exhaust gas is passed to the other reactor while oxygen is added thereto to oxidize the remainder and generate more heat. The heat of the gases and the additional heat of oxidation preheats scrap and carbonaceous material in that reactor.