The novel variant Lactobacillus bulgaricus sensitive at a lower temperature, that is, showing a weak tendency towards formation of lactic acid in a range of the lower temperature, and the method for the selection of the variant, are disclosed. By employing the variant, it is possible to produce a fermented milk or lactic acid beverage in which the rate of increase in the sour taste after preservation at a lower temperature is significantly lowered.Cultures of the variant Lactobacillus bulgaricus have been deposited with the Fermentation Research Institute, Agency of Industrial Science and Technology and accorded the number of FERM BP-1041.