To reduce supply heat quantity of reducing gas without using a pulverized coal burner by connecting a raw material combustion heater provided with an oxygen and combustion air supply unit to a fluidized bed reducing furnace, forming a raw material supply unit, burning coal material of the raw material, heating the raw material and supplying it.

Supplied raw material is reduced in a fluidized bed formed with high temperature reducing gas diffused from a reducing gas diffusing part 6 of a lower part of a furnace. Most of reduced particles are raised in the furnace 5 together with the gas, and transferred to an external circulating unit 7. The reduced particles and reducing exhaust gas are separated by a primary cyclone 8 and a secondary cyclone 9. The reduced particles are lowered in descending tubes 10a, 10b, returned to the furnace 5 via a pneumatic feeder 11, and proceeded in the reducing. Zinc and lead in iron making dust are reduced and volatilized in a reducing step to become gaseous state, guided to an exhaust gas disposal facility together with the reducing exhaust gas, and the particles are removed from a molding discharge port 12.