In order to restore the degenerated or weakened sporulation ability of saké yeasts, the following procedure was found to be recommended: The transplantations of yeasts are repeated 7-8 times each at intervals of 2-3 days and then more 2-3 times each at intervals of 7 days (or longer) in the koji extract which has not been sterilized by heat but has been freed from microörganisms by filtering with the Berkfeld's filter. 2. The percentage of staining of yeasts with methylene blue increased up to a maximum value on about the seventh day after inoculation and then decreased gradually. 3. The optimum temperature of the preculture to secure the highest sporulation percentage of saké yeasts lay near the maximum temperature of their multiplication.