To easily view the inside of a furnace from a tuyere for combustion gas without causing any trouble in supplying a cooling medium to a combustion gas flow.

In this gasification melting furnace, a gasified object and cokes are thrown in the gasification melting furnace, combustion gas is blown from the tuyere formed in a furnace side wall into the furnace to partially burn the gasified object. Thus, an inflammable gas is generated, and residues are molted at a hearth part and discharged to the outside of the furnace. A pipe 13 for supplying a cooling medium is connected midway to the conduit 12 for combustion gas feeding the combustion gas to the tuyere 3.