Inhibitory activities of 58 methanol extracts, which were prepared from different parts of 55 kinds of edible and medicinal plants, against human thrombin were evaluated. Analysis of the anti-coagulation activity determined by thrombin time enabled us to select 8 herb extracts as possible sources of anti-thrombosis agent. Further analysis of anti-thrombosis activity determined by activated partial thromboplastin time and fibrinolytic activity, and heat stability and inhibition against other proteolytic digestive enzymes provided new information that Pimpinella brachycarpa, Lysimachia clethroides, and Salix gracilistyla could be used as a potential anti-thrombosis agent. Our results suggest that edible and medicinal plants could be the potential source of thrombin inhibitor.