A humanized antibody against tissue factor (TF), comprising:A: a humanized H chain comprising (1) a H chain V region comprising the H chain CDRs of a mouse monoclonal antibody against TF and the H chain FRs of a human antibody, and (2) the H chain C region of a human antibody andB: a humanized L chain comprising (1) an L chain V region comprising the L chain CDRs of a mouse monoclonal antibody against TF and the L chain FRs of a human antibody, and (2) the L chain C region of a human antibody.After generating a humanized V region by grafting the CDRs of a mouse monoclonal antibody onto a human antibody, a humanized antibody having a higher activity is searched by replacing the FR of the above region with the corresponding FR of the human antibody having a high homology.