PURPOSE: To economize energy by directly coupling a heat holding furnace to the wall side on the material extracting side of a heating furnace provided with a walking beam type conveyor for feeding a material to the longitudinal direction in the furnace and transferring the heated billet to the heat holding furnace without removing the same.

CONSTITUTION: A billet is carried by a charging roll table 13 and is conveyed under heating up to the extracting side of a heating furnace 1 in the same way as in the prior art. The billet is then scopped up by a billet extracting machine 15 and is carried into a heat holding furnace 18 as the machine 15 is moved in the longitudinal direction of the furnace 18 without removing the same to the outsie of the furnace. The machine 15 is placed on a conveyance carriage 16 in order to move the billet in such a way and the carriage 16 moves on a rail 17 disposed in the longitudinal direction of the furnace 18.