Bacillus subtilis natto producing high level of a fibrinolytic enzyme was selected and Ultra Nattokinase$^{(R)}$ was manufactured by fermentation and purification. It was performed the evaluation of the antithrombotic effect of Ultra Nattokinase$^{(R)}$ (20,000 FU/g) with rat blood plasma. The maximum aggregation (inhibition ratio) was 71% (0%), 69% (2.8%), 62% (12.7%), 16% (77.5%) and 9% (87.3%), respectively, in the order of 0, 5, 10, 50 and 100 mg/mL of Ultra Nattokinase$^{(R)}$ solutions. Ultra Nattokinase$^{(R)}$ had antithrombotic effect, which was associated with the suppression of collagen-induced platelet aggregation. Ultra Nattokinase$^{(R)}$ in the topic of the FDP (fibrinogen degradation products) in blood coagulation tests showed a significant increasing trend. And based on the daily record of meal 39 people of ITT (what ?) group consisted with 19 people of NP (what ?) group and 20 people of PN (what ?) group except four people, two people who took vitamin K affecting the experiment and two people who took alcohol, finding to be taken Ultra Nattokinase$^{(R)}$ showed an increase in the FDP value after four weeks. In addition, FDP value of 41 people of ITT group except two people having metabolic syndrome was increased by Ultra Nattokinase$^{(R)}$.