PURPOSE: To provide a fluidized bed incinerator wherein a heat transfer pipe can be arranged so as not to corrode at high temperature, the pipe or the like is not worn away by frictional wear action to be caused by a fluidized medium, and the amount of the fluidized medium to be circulated is easily regulated.

CONSTITUTION: In the case where calorific rubbish or RDF is burnt, a layer is at a high temperature of 900°C to 950°C in an incinerator 3. As prevention against this fact, the temperature of the layer is made easy to control by circulating a fluidized medium 26 into a heat-collecting shell 23 which is connected with a communicating pipe 25 for the medium from the incinerator 3 and in which a heat transfer pipe 24 for collecting heat, is provided and slow combustion restraining the generation of CO is done by slowly moving the fluidized medium in the incinerator 3. Air is blown-in from an air-blowing pipe provided under the inside of the heat-collecting shell 23 and the fluidized medium 26 in the heat-collecting shell 23 is allowed to function as a fluidized bed, and hence residues containing chlorine component, which are corrosive, do not enter the inside of the fluidized medium 26. Furthermore, since the residues are sealed with the air blown-in, high-temperature corrosion to be caused with HCl on the heat transfer pipe 24 can be reduced.