The present invention provides an anti-human Notch4 antibody or a Notch4 binding fragment thereof that may have neutralizing activity against human Notch4, as well as a pharmaceutical composition comprising the same as the active ingredient. The present inventors obtained a mouse anti-human Notch4 antibody that has high neutralizing activity and binding affinity towards human Notch4 and determined the complementarity determining region (CDR) sequence of said mouse anti-human Notch4 antibody. This enabled the production of a humanized antibody comprising the variable region of heavy and light chains as well as the CDR sequence of said mouse anti-human Notch4 antibody.