Abstract: The present inventors examined the procoagulant activity of a multispecific antigen-binding molecule that functionally substitutes for FVIII using blood and plasma derived from FIX disorder patients. The result showed that multispecific antigen-binding molecules that functionally substitute for FVIII can be used not only as methods for preventing and/or treating bleeding in hemophilia A, acquired hemophilia A, von Willebrand disease, and hemophilia C, which are caused by FVIII dysfunction, but also as methods for preventing and/or treating bleeding in FIX disorders, because of their procoagulant activity. Furthermore, the effect of a FIX formulation could be enhanced by using it in combination with a multispecific antigen-binding molecule that functionally substitutes for FVIII, and it was shown that the combined use is promising as a combination therapy that shows stable hemostatic effects.