To efficiently obtain folic acid useful as a medicine, a raw material for medicines, a reinforcing agent for modified milk powder, a feed additive, an additive for culturing microorganisms, etc., by culturing a microorganism having an ability to produce the folic acid in the presence of a para- aminobenzoic acid derivative.

In this method for producing folic acid with a microorganism, the microorganism belonging to the genus Bacillus, Brevibacterium, Rhodococcus, Torulopsis, Saccharomyces, Pichia, Candida, etc., is cultured in the presence of a para-aminobenzoate such as a para-aminobenzoate alkali metal salt or a lower alkyl para-aminobenzoate. Thus, the folic acid useful as a medicine, a raw material for medicines, a reinforcing agent for modified milk powder, a feed additive, an additive for culturing microorganisms, etc., is effectively obtained.