To provide a waste melting device enhancing the volume reduction rate of wastes and contriving to extend the life of a final disposal plant.

A waste melting device comprises a melting furnace 1, a secondary combustion furnace 4 and an ash duct 5, and the melting furnace 1 comprises a furnace body 2 and a frame body 3 supporting it. The furnace body 2 is provided with a waste inlet 20, a waste storage zone 21 storing the wastes thrown in from this inlet 20 temporarily, a divided extruding device 23 extruding the wastes in this waste storage zone 21 to a furnace chamber 22, thermite agent input pipes 24 and 25 inputting a thermite agent to the wastes fallen onto a hearth part 23A comprising the furnace chamber 22, a side extruding device 26 bringing the wastes partially existing at both sides of the hearth part 23A to the vicinity right under the input pipes, a burner 27 igniting the thermite agent and an air injection part 28 accelerating the combustion of this burner 27.