For purpose of bioethanol production from citrus peel waste, simultaneous saccharification and fermentation (SSF) by the immobilized cells of Saccharomyces cerevisiae was studied. Limonene content had affected the ethanol production of S. cerevisiae free cells, but not that of immobilized cells. In the SSF of Citrus unshiu peel, ethanol production is not recognized in free cells. On the other hand, ethanol production is observed in immobilized cells. It was found that SSF by immobilized cells was useful for the bioethanol production from citrus peel waste.