Carbon iron composite is produced by feeding a formed product of a carbon-containing substance and an iron-containing substance into a carbonization furnace, carbonizing the formed product in a carbonization zone, blowing a coolant gas into the furnace through a coolant-gas-blowing tuyere disposed in a cooling zone to cool carbon iron composite, exhausting a furnace gas through an outlet in a top portion, and discharging the carbon iron composite through a lower portion of the cooling zone.