PURPOSE: To improve the responsiveness of control by maintaining the inside temperature of an incinerator at a preset value by the control of the rate of heating medium supply and controlling the addition of water to the waste and the rate of auxiliary fuel supply to the incinerator in a transient period.

CONSTITUTION: The inside temperature of the incinerator 4 is monitored by a temperature detector 14 connected thereto. When the temperature detector 14 detects out a temperature out of the preset range of value, the rate of heating medium 17 supply is controlled by a heating medium controller 16 so as to maintain the inside temperature of the incinerator 4 within the preset range of value. At the same time, the addition of water to the waste is controlled by a overheating controller 10 and also the rate of auxiliary fuel 8 supply to the incinerator 4 is controlled by an auxiliary fuel controller 7, so that the inside temperature of the incinerator 4 restores to the preset value quickly. Thus, the responsibility of the control can be much improved.