It was reported that angiotensin-converting enzyme (ACE) plays an important role in increasing blood pressure. Recently, it was reported that several food hydrolysates have ACE inhibitory effects in the spontaneous hypertensive rat (SHR) model and mildly hypertensive subjects. Therefore, the anti-hypertensive effects of brewers yeast BY-G were investigated, which contains many kinds of beneficial nutrients (vitamins, minerals, nucleic acids, glutathione, amino acids, etc.). The aim of this study was to evaluate the anti-hypertensive effects of BY-G and i ts component peptides obtained by enzymatic treatment. The peptide fraction KRF814 was obtained by the hydrolysate of BY-G with alkaline protease and then treated with Amberlite XAD-2. The KRF814, which has an inhibitory effect on ACE in vitro, was obtained. BY-G and KRF814 were fed to male SHR and showed significantly anti-hypertensive effects. KRF814 contained alanyl-phenylalanine (AF) and glycyl-phenylalanine (GF), which significantly decreased systolic BP in the SHR model. The active ingredients of KRF814, AF, and GF had about 60% of the potency of the positive control, which was captopril. It i s considered that intake of BY-G or its component peptides as a functional food stuff might be beneficial for improving BP in people with hypertension.