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.本發明提供一種對於人類Notch4可具有中和活性之抗人類Notch4抗體或其Notch4結合片段、及含有該等作為有效成分之醫藥組合物。本發明者等人獲取對於人類Notch4具有高中和活性及結合親和性之小鼠抗人類Notch4抗體，並特定出該小鼠抗人類Notch4抗體之互補決定區(CDR)之序列。藉此，可製作於重鏈及輕鏈之可變區包含上述小鼠抗人類Notch4抗體之CDR序列的人類化抗體。
