A method for breeding yeast having thermotolerance or recovering growth activity and a method for breeding yeast which produces beta-glucan efficiently as well as an yeast obtained by such methods for breeding are presented by a method for breeding yeast having thermotolerance or recovering growth activity including a step for controlling proofreading function of DNA polymerase in a loss-of-function mutant of yeast (for example, a step for including mutant pol3 gene or mutant cdc6-gene in a gene-disruptant.