A polypeptide complex comprising: (1) a cancer antigen binding domain； (2) any one of the Fc domains of SEQ ID NOs: 23, 24, 25 and 26 in which an amino acid (s) that forms the Fc domain is mutated, wherein the Fc domain mutant has reduced Fcγ receptor binding activity by said mutation compared to the control polypeptide complex comprising the Fc domain of the same isotype selected from SEQ ID NOs: 23, 24, 25 and 26, and where the Fc domain mutant has reduced FcγRI, FcγRIIA, FcγRIIB, FcγRIIIA, and / or FcγRIIIB binding activity； and (3) a CD3 binding domain, wherein the antigen binding domain and the CD3 binding domain are each a monovalent Fab, and where (i) the heavy chain Fv fragment of a monovalent Fab that The antigen binding domain form is linked to one of the polypeptides that form the Fc domain through a CH1 domain and the Fab light chain Fv fragment is linked to a CL domain； and the Fab heavy chain Fv fragment that forms the CD3 binding domain is linked to the other polypeptide that forms the Fc domain through a CH1 domain and the Fab light chain Fv fragment is linked to a CL domain； (ii) the heavy chain Fv fragment of a monovalent Fab that forms the antigen binding domain is linked to one of the polypeptides that form the Fc domain through a CH1 domain and the Fab light chain Fv fragment is linked to a CL domain； and the Fab light chain Fv fragment that forms the CD3 binding domain is linked to the other polypeptide that forms the Fc domain through a CH1 domain and the Fab heavy chain Fv fragment is linked to a CL domain； (iii) the heavy chain Fv fragment of a monovalent Fab that forms the antigen-binding domain is linked to one of the polypeptides that form the Fc domain through a CH1 domain； the Fab light chain Fv fragment is linked to a CL domain； the Fab heavy chain Fv fragment that forms the CD3 binding domain is linked to the other polypeptide that forms the Fc domain through a CL domain； and the Fab light chain Fv fragment is linked to a CH1 domain；
