PROBLEM TO BE SOLVED: To provide means for protecting Bifidobacterium bacteria in a capsule formulation from gastric acid penetrating through the capsule coating, without providing enteric coating.SOLUTION: The invention provides a capsule formulation comprising a capsule and a composition included therein, where the capsule comprises a water-soluble film-forming polymer and gellan gum, and the composition comprises Bifidobacterium bacteria and oil. Also provided is a preparation method thereof.SELECTED DRAWING: None