According to the present invention, there is provided a means of expressing and displaying a protein on the cell surface of a bifidobacterium. In the gene for expressing a protein on the surface of a bifidobacterium of the present invention, a gene coding for a bifidobacterium-derived GNB/LNB substrate-binding membrane protein and a gene coding for the target protein or peptide are linked in this order from the 5′ end side. Thus, a bifidobacterium transformed by introducing the gene for expressing a protein on the surface of a bifidobacterium of the present invention expresses the target protein or peptide on the surface thereof. When the target protein or peptide is an antigen protein or an antigen peptide, the transformed bifidobacterium of the present invention is useful as an oral vaccine.
