<;P>;PROBLEM TO BE SOLVED: To provide a new genus Bifidobacterium microorganism inhibiting the differentiation of Th17, inhibiting the production of IL-17, and utilizable for a food and drink, a medicine or the like. <;P>;SOLUTION: The genus Bifidobacterium microorganism containing 16SrRNA gene having a specific base sequence is regulated so that the amount of produced interleukin-17 in the supernatant, obtained by mixing mouse spleen cells, the heat-sterilized microorganisms, transforming growth factor beta and interleukin-6, and culturing the resultant mixture for 72 h, may be &le;30% of that obtained when the microorganism is not added. <;P>;COPYRIGHT: (C)2011,JPO&INPIT