PURPOSE: To miniaturize the device and to reduce the cost by executing the control of a height position of a melting tank and a casting material replenishment by a driving mechanism and an ingot replenishing mechanism and controlling prescribed molten metal pressure, in a molten metal supply device to a casting mold.

CONSTITUTION: A height position of a melting tank 1 and a replenishment of a casting material to the melting tank 1 which exest influence on supply pressure of a molten metal supplied into a cavity of a casting mold 21 are controlled by a driving mechanism 3 and an ingot replenishing mechanism, based on detection values of a tank position detector 15 and a tank weight detector 13. In such a way, in order to obtain prescribed molten metal pressure, an operation of both the mechanisms can be in an optimum state, the molten metal quantity in the melting tank 1 can be set to the necessary minimum, the molten metal supply device can be miniaturized and the cost can be reduced.