Bispecific antibody

Patent Granted [Problem] The purpose of the present invention is to provide a bispecific antibody that is structurally stable, and can show alone a sufficient effect without the co-administration of activated lymphocyte (T-LAK). [Solution] The present invention is therefore related to a humanized highly functional bispecific antibody comprising humanized variable regions of the heavy chain (5H) and the light chain (5L) of an anti-human EGF receptor 1 antibody 528, and humanized variable regions of the heavy chain (OH) and the light chain (OL) of an anti-CD3 antibody OKT3.