[Problem] To provide an anti human Ig antibody in which BCR and FcRIIb are crosslinked and which has a more enhanced immunosuppressive function compared to conventional antibodies. [Solution] An anti human Ig antibody including: a heavy chain variable region that includes a CDR 1 comprising an amino acid sequence from amino acid numbers 31 35 of SEQ ID NO: 2 a CDR 2 comprising an amino acid sequence from amino acid numbers 50 65 of SEQ ID NO: 2 and a CDR 3 comprising an amino acid sequence from amino acid numbers 98 108 of SEQ ID NO: 2 a light chain variable region that includes a CDR 1 comprising an amino acid sequence from amino acid numbers 24 38 of SEQ ID NO: 4 a CDR 2 comprising an amino acid sequence from amino acid numbers 54 60 of SEQ ID NO: 4 and a CDR 3 comprising an animo acid sequence from amino acid numbers 93 101 of SEQ ID NO: 4 and a heavy chain constant region said region being a human Ig1 constant region having S239D H268D and L328W amino acid variations.
