Formation of thrombi is a complex biological event involving platelets and coagulation cascades. The both have been well investigated individually. However, the interrelationship between them is still to be elucidated. The recent progresses in computer technology may allow us to simulate complex biological phenomena in silico. Here we report a novel method to reproduce the complex system of the interrelationship between platelet and coagulation by combining the previous simulation model of platelet adhesion with the model of coagulation cascade. We have reproduced the biological process of thrombus growth occurring in the mice cremasteric artery induced by endothelial injury by FeCl 3 with our newly developed computer simulator.