PURPOSE: To reduce fuel consumption and to prevent the equipment from being damaged in heating steel material to a prescribed temp. in a multizone heating furnace, by igniting burners in the heating zone and soaking zone at the same time, and by extinguishing the burners with the damper of a flue closed so as to lowers the temp. of the furnace slowly.

CONSTITUTION: A steel material 8 is heated to a prescribed temp. in a multizone heating furnaces composed of a preheating zone PM, a heating zone H, and a soaking zone S, by igniting simultaneously the upper burners 4, 3 and the lower burners 7aW7c, 6aW6d of the heating zone H and the soaking zone S. Ignition of the upper burners 2 and the lower burners 5aW5c of the preheating zone PH after a predetermined time causes to raise the temp. to a prescribed temp. of 1250°C in a short time. In extinguishing the burners, only the upper burners 4 of the soaking zone and upper burners 3 of the heating zone H are continued to burn until a prescribed time after the close of the flue damper 14 in order to lower the furnace temp. slowly. This method prevents the development of defects such as skid due to the rapid fall of furnace temp., and decresses remarkably the fuel consumption.