The object is to provide a lactic acid bacterium belonging to the genus Lactococcus, which has a high anti-inflammatory effect on an inflammatory bowel disease. Thus, provided are: a lactic acid bacterium belonging to the genus Lactococcus as typified by Lactococcus lactis OLS3301 strain and/or a processed product of the lactic acid bacterium； an immunoregulatory function inducer comprising the lactic acid bacterium and/or the processed product of the lactic acid bacterium as an active ingredient； and a food composition containing an effective amount of the lactic acid bacterium and/or the processed product of the lactic acid bacterium. The bacterium and/or the processed product thereof is capable of causing an immunocyte to produce IL-10, which is an anti-inflammatory cytokine, in a large quantity, and therefore can prevent an inflammation caused by an excess inflammatory response. The bacterium and/or the processed product thereof can also prevent an inflammation in the skin.
