PURPOSE: To be able to make stable burning in spite of the change in charged quantity etc. by burning while keeping temp. within a specified range when materials to be burnt are transferred, crushed, and then thrown into a fluidized layer.

CONSTITUTION: After materials to be burnt are transferred by a feeder 5 and crushed by a crusher 10 placed at the discharge hole 9 of the feeder, the materials are supplied on air distribution pipes 2 through an input hole 4 and fluid medium 11 such as sand etc. is supplied from a circulation line 20. Fluidizing air flowing from an air supply pipe 13 for fluidization is spouted from the pipe 2 and fluidizes the materials 3 and the medium 11 to form a fluidized layer 14. As the materials to be burnt are disassembled properly, their fluidized condition is made satisfactory. When temp. is raised up by an ignited burner and reaches 500°C or more, the materials are burnt by themselves with air for fluidization from the pipe 2. Stable burning is carried out in spite of the changes in charged quantity or waste quality in such a way that the temp. of the layer 14 is kept in the range of 520W650°C by water mist etc. from a water spray tube 24.