<;P>;PROBLEM TO BE SOLVED: To provide a highly safe pharmaceutical and a food and drink having actions of suppressing the production of IL-12 (interleukin 12) in an overproduction state of the IL-12 and ingestible over a long period of time. <;P>;SOLUTION: An IL-12 production inhibitor comprises a peptidoglycan or a protoplast derived from a bacterium or a zymosan derived from a yeast as an active ingredient. <;P>;COPYRIGHT: (C)2008,JPO&INPIT