PURPOSE: To maintain automatically the melt level for melting at a set reference melt level by bringing down two electrodes according to a timer, searching the position of the melt level at every prescribed time and replenishing a required amt. of molten metal.

CONSTITUTION: A set of electrodes 1, 2 are brought down according to the set time of a timer 7, and when the electrodes contact with the melt level of molten metal 16, a detector 3 detects the contact and stops the descending of the electrodes 1, 2. At the same time, the integrated number of pulses corresponding to the descending rate of the electrodes 1, 2 is fed from a pulse oscillator 9 to pulse counters 11, 12, 13 for an upper limit level, intermediate limit level and lower limit level. The three kinds of the pulse counts are discriminated with a signal discriminator 19, which instructs the valve opening of a burner 13, so as to replenish a required amt. of the molten metal. The melting rate of the material is thus controlled and the melt level for melting is maintained always at the set reference melt level.