Nattokinase is known to accelerate the fibrinolytic activity in vasculature owing to the cleaving of fibrin clots to plasminogen activator inhibitor type 1. Furthermore, it was also reported to cleave to fibrinogen, but the coagulation activity of the fibrinogen degradation produced by nattokinase was not known. In this study, we established that the fibrinogen degradation produced by purified nattokinase from vegetable cheese natto was injured to the regulated activity of fibrin clot formation. (author abst.)