PURPOSE: To provide a billet heat treatment device which realizes the energy saving, the space saving and the cost saving.

CONSTITUTION: The device is composed of a pre-heating furnace 4 which rapidly heats a billet to an intermediate temperature and a heating furnace 1 which heats the billet from the intermediate temperature to a set temperature, the pre-heating furnace 4 is interposed on an introducing path to the heating furnace 1, and it has a surface burner 3 which covers a hearth P and has caloric capacity to heat the billet to a higher temperature than the set temperature. In the heating furnace 1, a driving means which is one of constituting elements of an infurnance transferring means is also composed of an eccentric rotary plate 7 which sends a movable beam 6 to a prescribed direction on the circumferential face formed in a smooth curve and a reciprocation lever 8 which slides the movable beam 6 on the circumferential face of the eccentric rotary plate 7 synchronously with the rotary motion of the eccentric rotary plate 7 while connected to the movable beam 6.