The present inventors succeeded in improving, with respect to an antibody constant region, the stability under acidic conditions, heterogeneity derived from disulfide in a hinge region, heterogeneity derived from H chain C-terminus, and stability in a high concentration of a preparation. Further, they succeeded in finding the sequence of a novel constant region in which the binding to an Fc? receptor was reduced while minimizing the appearance of a novel T-cell epitope peptide. With these, they succeeded in finding an antibody constant region in which physical properties (stability and homogeneity), immunogenicity, safety, and pharmacokinetics were improved.
