To provide an apparatus which can decompose a large amount of various kinds of organic waste completely and can be installed in a narrow place due to its simple structure and to reduce the construction costs of the apparatus.

A hopper is installed above one end part of a fermentation decomposition apparatus. The apparatus comprises a fermentation decomposition means in which a fermentation adjustment chamber located below the hopper, a first fermentation decomposition chamber, and a second fermentation decomposition chamber are connected continuously and integrally to be able to rotate freely, a circulating means for conveying a bedding material from the terminal part of the fermentation decomposition means to the hopper, and a pollutant removing means for decomposing generated gas. An air hole is formed on the outer surface circumference of each connection part of the fermentation decomposition means. The transfer plate of a belt-shaped thin plate is fitted spirally on the inner surface of the fermentation decomposition means.