Antiobesity, hypotriglyceridemic and antihypertensive activities of isoflavone-free peptide mixture (black soybean peptide, BSP) were reported in our previous experiments. In the present study, angiotensin converting enzyme inhibitory (ACEi) activity was decreased in the aorta tissues of spontaneously hypertensive rats (SHRs) treated with BSP (1% in drink water) for 4 weeks, but not in serum. BSP administration significantly decreased ACE activity by 17.5% (from $33.2{pm}4.5$ to $27.4{pm}1.96$ mUnit/mg, p=0.0013) in aorta tissue hydrolysate. BSP treatment also decreased significantly mean blood pressure (BP) (from $213.0{pm}16.96$ to $184.0{pm}6.53$ mmHg, p<0.0001) as expected. These results indicate that BSP has antihypertensive activity as well as ACEi activity.