To carry out efficient decomposition by fermentation bacteria and simultaneously carry out culture of useful fermentation bacteria by making a cluster of water which is a medium, and an organic material ultrafine.

Facilities 1 for culturing fermentative bacteria are composed of a spawn tank 2 in which fermentative bacteria strains are stored, an additive tank 3 for additives containing syrups, a water-hyperfining apparatus 4 for receiving supply of water supply (w) and making a cluster of the water supply (w) ultrafine by shearing action by the large difference of water current speed of high-speed water current produced by a pump P2 and impulse force by a rotator, a fermentative bacteria-culturing tank 5 for culturing fermentative bacteria in large amounts by each feeding the fermentation bacteria strains, the additives and the water supply of hyperfining cluster from above tanks 2 and 3 and the hyperfining apparatus 4, organic material-pulverizing apparatuses 6 and 7 for receiving supply of the organic material such as waste food and pulverizing the organic material, a solubilizing apparatus 9 for making the pulverized organic material and water cluster ultrafine by the same principle as the above apparatus 4 and a fermentation promoting tank 10 for culturing the fermentative bacteria from the fermentative bacteria-culturing tank 5 by the ultrafine organic material and water and treating the organic material.