There is provided a fermented milk product that contains lactic acid bacteria capable of producing a large amount of lactotripeptide and a large amount of active ingredient having hypotensive activity and anti-stress effect, and that can be taken pleasantly as foods or beverages. Lactic acid bacteria of Lactobacillus helveticus having specific bacteriological properties, the bacteria, when cultured in a medium of animal milk containing 9 wt % solid of non-fat milk, producing tripeptides Val-Pro-Pro and Ile-Pro-Pro in an amount of 60 .mu.g in terms of Val-Pro-Pro per ml medium, and the bacteria exhibiting extracellular proteinase activity of not lower than 400 U/OD.sub.590. Lactobacillus helveticus CM4 strain (deposited at National Institute of Bioscience and Human-Technology Agency of Industrial Science and Technology, deposition number FERM BP-6060). A fermented milk product obtained by fermenting an animal milk with these lactic acid bacteria.