A high-protein-containing organic product is manufactured by decomposing and removing, at low cost and high processing capacity, phorbol ester from a phorbol ester-containing organic product. The phorbol ester in the organic product is decomposed by mixing and fermenting the phorbol ester-containing organic product with a bacteria of the genus bacillus. In the fermentation process, the phorbol ester is preferably decomposed by mixing a pre-culture of some of the phorbol ester-containing organic product and bacteria of the genus bacillus, then preparing a separate mixture of the phorbol ester-containing organic product and bacteria of the genus bacillus, and adding the pre-culture to the mixture to carry out the main fermentation.
