Effects of alcohol and organic acid contents and of temperature on the viability of yeast during resting period ( karashi ) were investigated, and following results were obtained: (1) The viability of yeast in seed mash was reduced by the presence of alcohol and organic acids, and by the rise of temperature, the effect of alcohol being most marked. (2) A method was developed to avoid viability loss.The method consisted of diluting the seed mash with twice its volume of water at the beginning of resting period ( wake ) and keeping it at low tempeature.