© Springer Japan 2015.Bioethanol is one of the most important renewable fuels for the reduction of global warming effects and environmental damage caused by the worldwide utilization of fossil fuels. Yeasts such as Saccharomyces cerevisiae are frequently used for bioethanol production from mono- or disaccharides derived from biomass, including sugar cane, corn, and lignocellulosic materials. During bioethanol production, yeast cells are exposed to various environmental stresses including chemical, temperature, oxidative, and acid stresses. The development of yeast strains tolerant to such environmental stresses must improve the bioethanol production process. This chapter focuses on the environmental stresses to which yeast cells are exposed during bioethanol production. We also discuss the exploration and breeding of stress-tolerant yeast strains and their application to bioethanol production.