PROBLEM TO BE SOLVED: To provide a technology to inhibit the growth of Bilophila bacteria, being highly safe and free of influence on the balance of intestinal flora.SOLUTION: An inhibitor of the growth of Bilophila bacteria of which effective component is a Bifidobacterium is provided. Also provided is a method for inhibiting the growth of Bilophila bacteria using a Bifidobacterium as an effective component. As the Bifidobacterium, Bifidobacterium longum ATCC BAA-999 may be used.SELECTED DRAWING: None