For the purpose of obtaining a yeast strain which accumulates a large amount of L-lysine in molasses medium, a 2-aminoethylcysteine-resistant mutant, KY 5545, was hybridized with the haploid, YOY 50, derived from a baking strain. Spore clones isolated from this diploid were mated each other, and one of the strain, YOY 783, was selected. YOY 783 accumulated about 6% of Llysine in the cells on dry matter basis when cultured in the molasses medium, whereas it accumulated only a small amount comparable to that of its parental strains when cultured in YPD medium.