PURPOSE: To rapidly dry even garbage with high moisture content by heating the org. waste charged to a receiving tank under stirring by hot air and providing a hot air generating furnace to the bottom part of the receiving tank in a direct contact state.

CONSTITUTION: Org. waste such as garbage to be treated is charged to a receiving tank 1 by opening the charging hatch 2 provided to the upper part of the tank 1. A motor is started to rotate the stirring blade 12 of a stirring mechanism and the org. waste is stirred. At the same time, the heating source 6 of a hot air generating furnace 4 is started to start heating and a blower 7 is operated to inject the hot air of the hot air generating furnace 4 into the lower part of the receiving tank 1 and the air in the tank is circulated between the tank and the hot air generating furnace 4. By this method, the org. waste in the tank receives hot air under stirring to be heated. Since the hot air generating furnace 4 is provided to the bottom part of the receiving tank 1 in a direct contact state, the heat of the heating source 6 is well conducted to the bottom part of the receiving tank l and the receiving tank 1 is also directly and effectively heated by conduction heat.