The present invention provides a human antibody against blood coagulation factor VIII (hereinafter also referred to as "FVIII") and an antibody fragment that binds to human FVIII and specifically inhibits the coagulation activity of human FVIII. ScFv display phage libraries, prepared by using scFv DNAs constructed by random combinations of immunoglobulin VH chain genes and VL chain genes from lymphocytes from hemophilia A patients, is reacted with FVIII immobilized to a solid phase via anti-FVIII monoclonal antibody, and scFv clones capable of binding to FVIII are cloned to reveal VH and VL chains of FVIII-specific antibody.