Various bispecific antibodies that specifically bind to both blood coagulation factor IX/activated blood coagulation factor IX and blood coagulation factor X and functionally substitute for the cofactor function of blood coagulation factor VIII, that is, the function to promote activation of blood coagulation factor X by activated blood coagulation factor IX, were produced. From these antibodies, multispecific antigen-binding molecules having a high activity of functionally substituting for blood coagulation factor VIII were successfully discovered.本發明製作各種雙專一性抗體,其專一性地結合於血液凝固第IX因子/活化的血液凝固第IX因子及血液凝固第X因子兩者,且具有替代血液凝固第VIII因子之輔因子功能,亦即具有替代促進經活化的血液凝固第IX因子所為之使血液凝固第X因子活化之功能。該等抗體之中,成功發現替代血液凝固第VIII因子之功能的活性高的多重專一性抗原結合分子。