There is provided a method for processing green coffee beans capable of imparting new aromas and flavors to a coffee beverage using a simple operation, without incurring an increase in raw material costs.The method for processing green coffee beans includes a fermentation step of bringing nutritive substances included in coffee cherries and microorganisms into contact with one another and causing fermentation, and a collection step of separating and collecting green coffee beans from the coffee cherries that have undergone the fermentation step, wherein in the fermentation step, at least part of the pulp of the coffee cherries is exposed, and the microorganisms are caused to come into direct contact therewith.