An object of the present invention is to provide an antibody composition, which more selectively exhibits an effector function against a target cell coexpressing two types of antigens that are different from each other and damages the target cell, and also can maintain affinity for the individual target antigens sufficiently high. The present invention relates to an antibody composition against a first antigen and a second antigen that are different from each other, composed of a first IgG half-molecule and a second IgG half-molecule.