A bifidobacterium-expressing gene for expressing an immunogenic polypeptide on the surface of bifidobacterium. The gene includes a gene that codes immunogenic polypeptides. The immunogenic polypeptides include a prescribed base domain and at least one antigen peptide. The at least one antigen peptide is linked to either the N-terminal side or the C-terminal side of the base domain. This bifidobacterium-expressing gene can also include a gene that codes a bifidobacterium-derived GNB/LNB substrate-binding protein.
