A new fusion protein which can specifically suppress the autoantibodies, which can effectively prevent or treat the autoimmune disease of autoantibody type, and which can be expressed in an amount sufficient for industrial production. A fusion protein, characterized in that, a protein (X) containing a site recognized by autoantibodies which are a cause of the autoimmune disease of autoantibody type is connected to a protein (A) containing a fragment of the antibody heavy chain constant region which exhibits the antibody-dependent cellular cytotoxicity with a linker peptide (L) consisting of one or more amino acid(s), wherein the protein (X), the linker peptide (L) and the protein (A) are connected in this order by means of peptide bond from N terminal to C terminal.