The present invention provides a peptide capable of binding to an immunoglobulin, a fusion protein with the peptide, nucleic acids coding for the peptide and for the fusion protein, methods for producing the peptide and the fusion protein, and a composition and means for binding an immunoglobulin, as well as a pharmaceutical composition for the treatment or prevention of a disease caused by the binding between C1q and an immunoglobulin, which includes a peptide capable of binding to the immunoglobulin or a fusion protein with the peptide, and others.
