Disclosed is a method for producing an antimutagenic substance by using a lactic acid bacteria, which can produce the antimutagenic substance in a large quantity in an extremely simple manner and is economically advantageous； particularly a method for producing an antimutagenic substance effective for a carcinogenic substance, particularly a heterocyclic amine (HCA) which is a carcinogenic substance derived from a food, by using a lactic acid bacteria. Specifically disclosed is a method for producing an antimutagenic substance by using a lactic acid bacteria, which is characterized by suspending the lactic acid bacteria in a poorly nutrient or nutrient-free medium and leaving the lactic acid bacteria in the medium. Preferably, the poorly nutrient or nutrient-free medium is selected from the group consisting of physiological saline, a phosphate-buffered saline without a calcium or magnesium salt (PBS (-)), a citrate buffer, a distilled water, an ion-exchanged water, a natural water, a well water, a tap water, a mineral-added water, a vitamin-added water, an ion supply beverage for an athlete and the like. More preferably, the lactic acid bacteria is Lactobacillus plantarum strain KK-2503 or Lactobacillus alimentarius strain KN-15.
