To provide a novel antibody. Provided is a monoclonal antibody or a binding fragment thereof that binds to domain 3 of human LAG-3 and has one or more of the properties described in (ii) to (v), and the properties described in (i) and (vi) below: (i) having in vitro ADCC activity； (ii) reducing the number of LAG-3 positive cells in vivo in low fucose form； (iii) suppressing experimental autoimmune encephalomyelitis in vivo in low fucose form； (iv) binding to human activated T cells； (v) human LAG-3 binds to human major histocompatibility complex class II molecules in the presence of the antibody or the binding fragment thereof； and (vi) the presence of the antibody or the binding fragment thereof allowing human LAG-3 to exert a human T cell suppression function.
