The functional properties of Kome Shochu Kasu (KSK) fermented by Lactobacillus brevis IFO-12005 and enriched with γ-Aminobutyric acid were investigated. Fermented and concentrated (x 10) KSK containing heat treated lactic acid bacterial cells [Lac (+)] and not containing lactic acid bacterial cells [Lac (-)] was fed to spontaneously hypertensive rats (SHR) for ten weeks. The blood pressure in the fermented KSK groups, for both Lac (+) and Lac (-), was significantly lower than that in the control group, indicating that GABA suppressed an increase in blood pressure of SHR.