To provide a product having ammonia smell peculiar to Bacillus natto and diluted through adding Bacillus microorganism together with Bacillus natto when using soybeans as the raw material.

A method for producing fermented soybeans comprises preparing a product obtained by proliferating "Bacillus subtilis takemi" as Bacillus microorganism in a product obtained by pulverizing soybeans before producing fermented soybeans through adding Bacillus natto to soybeans, and proliferating Bacillus natto and the takemi at the same time. The takemi enables the product to have ammonia smell peculiar to Bacillus natto and diluted, and easy ingestion of active ingredient such as chitin.