TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The drum comprises a body (20) having through hole(s) (21a) so as to discharge moisture contained in the organic matters. The drum includes a screen (22) having a mesh for passing moisture through the through holes and filtering organic matters. The screen is attached to an inner or outer surface of the body. The organic matter disposer includes fermentative microbe supplying unit provided at an upper part of the drum so as to supply fermentative microbes to the organic matters. The driving device comprises a dehydrating axis coupled with the drum; a stirrer axis rotatably provided in the dehydrating axis and coupled with the stirrer; a clutching device provided to selectively connect the dehydrating axis with the stirrer (30); and a motor for rotating the stirrer axis. The stirrer axis comprises an upper stirrer axis connected with the stirrer; and a lower stirrer axis connected with the motor. The organic matter disposer includes a speed reducer provided between the upper stirrer axis and the lower stirrer axis so as to reduce rotational speed transmitted from the motor. The speed reducer comprises sun gear provided at an upper end of the lower stirrer axis; a planetary gear (141, 142, 143) connected with the sub gear; a first inner gear formed at a lower part of the upper stirrer axis so as to be selectively connected with the sun gear; and a second inner gear formed at a lower part of the first inner gear so as to be selectively connected with the sun gear. The clutching device comprises a coupling (45) provided to be movable up and down at an outer circumference of the lower stirrer axis so as to be selectively connected with the dehydrating axis; and a clutch for moving the coupling up and down.Preferred Methods: In the drying step, the stirrer is rotated at a reduced speed. In the dehydrating step, the drum and the stirrer are rotated at a same speed. The method includes before the drying step, a reheating step of preheating the heating device. The preheating and dehydrating steps are performed for a time preset in a controlling member and then automatically stopped. The drying step is performed for a time preset in a controlling member and then automatically stopped.