The present invention provides efficient methods based on alteration of the protein A-binding ability, for producing or purifying multispecific antibodies having the activity of binding to two or more types of antigens to high purity through a protein A-based purification step alone. The methods of the present invention for producing or purifying mufti specific antibodies which feature altering amino acid residues of antibody heavy chain constant region and/or variable region. Multispecific antibodies with an altered protein A-binding ability, which exhibit plasma retention comparable or longer than that of human IgG1, can be efficiently prepared in high purity by introducing amino acid alterations of the present invention into antibodies.
