The present invention provides a lactic acid bacterium which has high proteolysis activity and good peptide production ability and/or amino acid production ability and fermented milk containing amino acids and/or peptides at high concentrations and having a good flavor.Specifically, the present invention provides a lactic acid bacterium belonging to Lactobacillus helveticus having at least one of the following properties (a) to (d) of: (a) producing 25 µmol/ml or more of free amino acids by fermenting animal milk (b) producing 8.5 mg/ml or more of peptides by fermenting animal milk (c) producing 260 µg/ml or more in total of XP peptides and/or XPP peptides by fermenting animal milk and (d) producing 6.0 mg/g or more of IPP and VPP peptides, which amount is converted to the amount of VPP, per acidity of fermented milk that is obtained by fermenting animal milk at 30-34 °C. (Fig. 2)
