To provide a waste treatment apparatus performing stable volume reducing treatment in a high volume reducing ratio without increasing size of the apparatus.

Waste is charged in a fine particle heat treatment tank 10 from a charging port 11 to be stirred by a stirring blades 14. Herein, the fine particle heat treatment tank 10 is filled with a granular base material 17. Waste is stirred in a state mixed with the granular base material 17 by the stirring blades 14 to be crushed and finely divided. At this time, the fine particle heat treatment tank 10 is heated by a heater 15 and the garbage is dried. When the amount of the garbage in the fine particle heat treatment tank 10 becomes larger than a predetermined amount, the excess waste is supplied to a decomposition treatment tank 20 through a waste transfer port 16 to be biologically degraded by microorganisms.