To compact a furnace body without damaging the function, capacity, performance, etc., of the furnace and to reduce building cost of the furnace and radiating heat loss by fitting slit nozzle type burners or regenerative burners having thin thickness of the burner flame on the side walls of the whole control zone in a walking beam type metal heating furnace.

A metallic material 32 to be heated is carried with the walking beam driving device 15 along a furnace hearth line 31 of the furnace, and a first heating zone 3, second heating zone 4 and soaking zone 5 are continuously passed through in order to execute the heat treatment. In the walking beam type metal heating furnace, instead of circle nozzle type burners or regenerative burners having about 800-1500mm flame diameter, the slit nozzle type burners or the regenerative burners 13-18 having about 100-500mm thickness flat shape flame are fitted to the upper and the lower parts of the furnace hearth line 31 on the furnace side walls 8 in the whole control zones 3, 4, 5. By this constitution, the whole height 29 of the furnace is made to about 55%, the radiating heat loss from the furnace body surface is made to about 50 70% and the building cost is made to about 60-80% in comparison with the conventional furnace.