To provide a processing method that can effectively decompose organic waste, such as refuse, with aerobic bacteria.

This apparatus has a processing tank 2 of a bottomed cylinder whose upper opening serves as a charging port 2a and which contains a screw conveyor mechanism SC erected on the center of the bottom of the tank 2 and interlocking with a motor 20 and a collecting member 16 that is operated synchronously with the screw conveyor mechanism SC. A guide cylinder 17 having a prescribed diameter and a prescribed length is provided at an upper part of the screw conveyor mechanism SC to surround the screw conveyor mechanism SC to form a circulation path X between the guide cylinder 17 and the inner wall of the processing tank 2, so that air is supplied into the processing tank 2 along the screw conveyor mechanism SC. Organic waste and aerobic bacteria charged from the charging port 2a are circulated through the circulation path X by the screw conveyor mechanism SC and the collecting member 17 to be mixed uniformly and then are allowed to stand, so that the organic waste is decomposed to disappear, or reduced.