We carried out test brewing with two types of yeast to compare changes in visible cell counts and several components in moromi mash during fermentation. S. cerevisiae Hiroshima ginjo kobo(HG) and Kumamoto kobo KA-4(KA-4) were respectively used as an ethyl capronate high-producing yeast and an ordinary yeast, which has good fermentation ability, for high quality sake. Visible cell counts of HG were lower than those of KA-4 throughout the fermentation period. Percentages of visible cell counts of HG to total yeasts began to decrease at the early stage of fermentation and were approximately 10-60% at the middle stage of fermentation. As the ratio of the addition of HG to KA-4 to moromi mash for starter culture was higher, the alcohol content and acidity were lower and the baumè deceasing rate was slower during fermentation. In addition, ethyl capronate and capronate concentrations were higher, but ethyl acetate and isoamyl acetate concentrations were lower on flavor components throughout the fermentation period. Malate and succinate concentrations decreased in moromi mash on organic acids with increasing ratios of the addition of HG to KA-4 to moromi mash.