The present invention relates to a method of culturing a yeast including culturing the yeast in a liquid medium whose citric acid concentration is equal to or greater than 20 mM； a method of culturing a yeast as described above, wherein the citric acid concentration of the liquid medium at the initiation of the culture is lower than 20 mM, and the method includes a step of adjusting the citric acid concentration of the liquid medium at 20 to 200 mM during a time after the initiation of the culture until the termination of the logarithmic growth phase； and a method of producing a yeast extract, wherein the method includes a step of extracting a yeast extract from a yeast cultured by any of the aforesaid methods； and a method of producing a food or drink, wherein the method includes using, as a starting material, one or more products selected from the group consisting of a yeast cultured by any of the aforesaid methods and a yeast extract prepared from such yeast. The present invention is capable of providing a method of culturing a yeast, whereby the glutathione content in the yeast cells can be increased without applying genetic modifications.
