PURPOSE: To prevent the solidification of the molten liquid when it is discharged from the melt discharge part of a melting furnace for waste matter and thereby prevent the clogging of a discharge opening with the melt or its adherence to the discharge opening periphery.

CONSTITUTION: A raised part 13 is formed on the bottom part 12 of a molten liquid discharge part 11 of a melting furnace projecting inwardly of the furnace and a discharge opening 15 is provided in the top part 14 of the raised part 13. Since the discharge opening 15 is located at the top part 14 of the raised part 13, i.e., a high temp. part inside the furnace, this structure causes the temp. of the discharge opening 15 and its periphery to become sufficiently high to prevent the solidification of the molten liquid 16 discharged from the discharge opening 15. For this reason, there is neither clogging of the discharge opening 15 with the solidified molten liquid 16 nor its adherence to the periphery thereof.