The present invention addresses the problem of providing a fermented milk that shows a suppressed increase in acidity during cold storage and a method for producing the same and thus solving problems of conventional techniques, said fermented milk being able to be produced by a common production process within a fermentation time almost equal to the fermentation time in conventional methods without requiring any additives for promoting fermentation or suppressing an increase in acidity. Provided are: a lactic acid bacterium starter containing (a) a Lactobacillus delbrueckii subsp. bulgaricus strain that has such mycological properties that, when the strain is inoculated into a skim milk medium having been adjusted to pH 4.2-4.3 by adding lactic acid and then maintained at 35-47°C, 15 hours or longer are required to lower the pH of the medium by 0.2, and (b) a Streptococcus thermophilus strain that has such mycological properties that, when the strain is inoculated into a skim milk medium, cultured at 37-45°C for 12-24 hours and then cooled at 1-10°C, no aggregation is observed; a method for producing a fermented milk using the lactic acid bacterium starter; and a fermented milk produced thereby.