PURPOSE: To eliminate final disposal site by mounting a fermenting vat incorporating a multi-screw on the bed, then throwing in fermenting soil bacteria together with raw garbage thereafter heating and agitating on a truck and composting on the transporter.

CONSTITUTION: Raw garbage and fermenting soil bacteria are thrown into a fermenting vat on a truck, then a multi-screw 2 is rotated. Consequently, the raw garbage and the soil bacteria in the fermenting vat 1 are subjected to forward feeding through the main blade 6 and rearward feeding through return blade 7 of the multi-screw 2 thus being agitated and moved. At the same time, a heater 21 is operated to feed hot air into the fermenting vat 1 so as to heat the raw garbage and fermenting soil bacteria. Consequently, the fermenting soil bacteria are activated and the raw garbage is fermented. As a result, raw garbage is converted into powder remnant and composted. When raw garbage is composted on a truck, final disposal site is not required and hygienic processing can be carried out.