Abstract: Yeast extract is produced by using a strain of Saccharomyces cerevisiae, which can contain 1% by weight or more of &ggr;-glutamylcysteine and contains 0.004-0.1% by weight of glutathione during its logarithmic growth phase, when the strain is cultured in a medium in which a glutathione synthetase deficient strain shows a slower growth rate than a wild strain of Saccharomyces cerevisiae, for example, a strain of Saccharomyces cerevisiae, wherein glutathione synthetase encoded by a glutathione synthetase gene on a chromosome has deletion of a C-terminus region from the 370th arginine residue. There are provided yeast that can be used for production at industrial level and shows a high &ggr;-glutamylcysteine accumulation amount, and yeast extract produced by using the yeast.