Provided is a gene for expressing an immunogenic polypeptide on the cell surface of a bifidobacterium, and the gene includes a gene encoding the immunogenic polypeptide, the immunogenic polypeptide includes a predetermined base domain and at least one antigenic peptide, and the at least one antigenic peptide is linked on any of the N-terminal side and the C-terminal side of the base domain. The gene for expressing an immunogenic polypeptide on a cell surface of a bifidobacterium of the present invention can further include a gene encoding a bifidobacterium-derived GNB/LNB substrate-binding membrane protein.
