To provide a dust disposal device having superior heating efficiency.

This dust disposal device is composed of an inner cylinder 4 having a supply opening 4c for supplying dust including heavy metal, and a discharge opening 4d for discharging, and an outer cylinder 3 covering the inner cylinder 4. The outer cylinder 3 is provided with a microwave oscillator 5 for heating the dust 10 supplied into the inner cylinder 4, and the inner cylinder 4 has a microwave irradiation part composed of an electromagnetic wave transmitting material 4a, and is provided with a constant rate discharge mechanism 8 at its discharge opening 4d for allowing the dust 10 passing through the inner cylinder 4 to stay in the inner cylinder 4 for a prescribed time.