To provide a melting furnace apparatus for continuously feeding preheated material to be melted to the furnace by uniformly preheating the material and preventing clogging of the material and damage of a material supply unit.

The melting furnace apparatus comprises a melting furnace 1 rotatably provided around a substantially horizontal axial center L, a material supply unit body 4 having a material feeder 2 for feeding material to be melted into the furnace 1 and a material dropping unit 3 for dropping the material to the feeder 2, and a material preheater 9 having a moving means Z for forwarding or retreating the body 4 to or from the furnace and disposed above the unit 3 to be surrounded at its periphery with a cylindrical circumferential wall 25. In this case, exhaust gas G from the furnace 1 is fed into its interior from an inlet provided at an upper part of the wall 25, the material is preheated while passing down, and the gas G is exhausted from an exhaust port provided at a lower part of the wall 25.