The present inventors produced a heterodimerized polypeptide having an Fc region that comprises two polypeptides having different amino acid sequences from each other (i.e., a first polypeptide and a second polypeptide), and thus succeeded in the production of a heterodimerized polypeptide containing an Fc region having an improved function compared with that of a homodimer having an Fc region composed only of the first polypeptide or a homodimer having an Fc region composed of the second polypeptide which are conventional techniques.
