A method for judging the authenticity of the production region of an agricultural product, comprising: a first step of collecting of the benchmark soil, in which the benchmark soil is collected from a specific agricultural land; a second step of computing characteristic value for the benchmark soil, in which the suspension of benchmark soil is added dropwise to a plurality of nutrient sources, the rates of consumption of least some of which differ depending upon microbial species, in which quantity of the nutrient sources consumed by the microorganisms contained in the benchmark soil within a certain period is observed as cumulative consumption quantity of the benchmark soil, and in which characteristic values for the benchmark soil for all nutrient sources are computed; a third step of collecting of the soil to be tested in which the soil attached to the agricultural products for which the specific agricultural land is labelled as a production region as the soil to be tested is collected; a fourth step of computing characteristic value of the soil to be tested in which the suspension of the soil to be tested is added dropwise to the same types of nutrient sources as those used in the second step of computing characteristic value of the benchmark soil, in which quantity of the nutrient sources consumed by the microorganisms contained in the soil to be tested within a certain period is observed as cumulative consumption quantity of the soil to be tested, and in which characteristic values related to the soil to be tested for all nutrient sources are computed; and a final step of determination regarding deception, in which characteristic value percentages are computed for the nutrient sources in the soil to be tested and the benchmark soil, each characteristic value percentage being represented by a ratio of the characteristic value for one of the nutrient sources to an average of the characteristic values for all nutrient sources, the characteristic value percentages for the soil to be tested are compared with the characteristic value percentages for the benchmark soil, and thereby, the labelling of production region for agricultural products is judged to be false in case that a difference between the two exceeds a predetermined standard. a first step of collecting of the benchmark soil, in which the benchmark soil is collected from a specific agricultural land; a second step of computing characteristic value for the benchmark soil, in which the suspension of benchmark soil is added dropwise to a plurality of nutrient sources, the rates of consumption of least some of which differ depending upon microbial species, in which quantity of the nutrient sources consumed by the microorganisms contained in the benchmark soil within a certain period is observed as cumulative consumption quantity of the benchmark soil, and in which characteristic values for the benchmark soil for all nutrient sources are computed; a third step of collecting of the soil to be tested in which the soil attached to the agricultural products for which the specific agricultural land is labelled as a production region as the soil to be tested is collected; a fourth step of computing characteristic value of the soil to be tested in which the suspension of the soil to be tested is added dropwise to the same types of nutrient sources as those used in the second step of computing characteristic value of the benchmark soil, in which quantity of the nutrient sources consumed by the microorganisms contained in the soil to be tested within a certain period is observed as cumulative consumption quantity of the soil to be tested, and in which characteristic values related to the soil to be tested for all nutrient sources are computed; and a final step of determination regarding deception, in which characteristic value percentages are computed for the nutrient sources in the soil to be tested and the benchmark soil, each characteristic value percentage being represented by a ratio of the characteristic value for one of the nutrient sources to an average of the characteristic values for all nutrient sources, the characteristic value percentages for the soil to be tested are compared with the characteristic value percentages for the benchmark soil, and thereby, the labelling of production region for agricultural products is judged to be false in case that a difference between the two exceeds a predetermined standard.