An objective of the present invention is to provide an Fc region variant with enhanced FcyRIIb-binding activity, and/or enhanced binding selectivity to FcyRIIb compared to FcyRIIa (type R), as compared to those of a polypeptide containing an Fc region to which an amino acid alteration(s) has not been introduced； a polypeptide which includes the Fc region variant； a pharmaceutical composition containing the polypeptide； preventing therapeutic or preventive agent for immunological inflammatory diseases that includes the pharmaceutical composition； a production method thereof； and a method of enhancing FcyRIIb-binding activity and also enhancing binding selectivity to FcγRIIb compared to FcγRIIa (type R).It was found that a polypeptide containing an antibody Fc region variant that contains an amino acid sequence in which an amino-acid alteration at position 238 (EU numbering) is combined with other specific amino-acid alterations enhances FcyRIIb-binding activity, and/or enhances binding selectivity to FcγRIIb compared to FcγRIIa (type R).
