PROBLEM TO BE SOLVED: To provide an agent for the prevention and treatment of inflammatory bowel disease containing bacteria of the genus Lactobacillus or a polysaccharide fraction derived from the bacterial cell as an active component, an IL-6 formation suppressing agent containing the treating agent as an active component and an agent for suppressing IL-6/STAT3 phosphorylation response containing the same. SOLUTION: The above problems are solved based on the findings that lactobacillus or a polysaccharide fraction derived from the bacterial cell has excellent effect for the prevention and treatment of inflammatory bowel disease and the mechanism of the action is the suppression of IL-6/STAT3 phosphorylation response based on the IL-6 formation suppressing action.
