Biologically active peptides as components in functional foods exhibit diverse activities and exert health effects in humans, just as the angiotensin I-converting enzyme (ACE)-inhibitory peptide exerts an antihypertensive effect. The solid-state fermentation of soybean meal was conducted using Bacillus subtilis natto at an appropriate temperature to accelerate proteolytic hydrolysis, and the crude extract containing ACE-inhibitory peptides was sequentially purified by ultrafiltration, gel chromatography and reverse phase-HPLC. A novel ACE-inhibitory peptide was obtained and its ACE-inhibitory activity was 84.1% with an IC ₅₀ value of 0.022 mg/ml. The results suggest that these ACE-inhibitory peptides obtained from the solid-state fermentation of soybean meal using B. subtilis natto have good potential for application in the management of hypertension and the fermented soybean meal has good potential for application in the production of a novel physiologically functional food.