The yeast which has .gamma.-glutamylcysteine-producing ability and is auxotrophic for pantothenic acid is proliferated in a medium containing a sufficient amount of pantothenic acid, and then it is cultured in a medium containing a limited amount of pantothenic acid to increase the .gamma.-glutamylcysteine content in its cells, whereby the yeast in which .gamma.-glutamylcysteine is accumulated is obtained.