A method for producing a rich taste imparting substance-containing yeast, where the method includes: a yeast proliferating step of culturing a yeast that is modified to have a reduced acetolactate synthase activity in cells, and has isoleucine and valine requirements in a culture medium containing isoleucine and valine, to proliferate the yeast; and a rich taste imparting substance producing step of culturing the yeast with addition of valine to the culture medium when an isoleucine content in the culture medium is less than 0.2% by mass, to produce a rich taste imparting substance, wherein the rich taste imparting substance is at least one of γ-Glu-Abu and γ-Glu-Abu-Gly.