To provide a fermentation method capable of producing good quality compost having high application safety which does no harm to plants when it is applied to green farmland in a shorter fermentation period compared with a conventional method, downsizing a fermentation tank and facility and realizing reduction of a running cost.

The fermentation method for organic waste is a method for fermenting a mixture of organic waste and chaff. The first fermentation first process 2 in which fermentation lasts for 3-10 days is carried out. All the obtained processed materials are transferred to the second fermentation process 3 in which fermentation lasts for 3-10 days. All the obtained processed materials are transferred to the third fermentation process 4 fermentation lasts for is not more than 30 days.