We estimated amylase in the filtrate of Sake-mashes, which were prepared with “Taka-diastase” or “Koji” and investigated the behavior of amylase during mash fermentation.The results were as follows:1) Sake mash can be prepared with “Taka-diastase” without the use of “Koji”, but the fermentation of this mash is slow. The acid content of this mash is smaller and the color is lighter in comparison with the usual mash, prepared with “Koji”.2) Activity of α-amylase in “Taka-diastase” mash is strong in initial stage, but falls rapidly after 5 or 6 days. When we add the “Taka-diastase” to this mash, its activity becomes strong again, but falls soon.3) On the contrary, α-amylase activity in the usual mash falls slowly and it remains to some degree also in final stage.4) Saccharifying power in both mashes shows stable values in the wohle stage when compared with α-amylase activity.5)α-amylase moves to Sake-residue (i. e. unfermentable solid matters in mash) jn great quantities, especially in “Taka-diastase” mash. This fact shows that α-amylase is easily absorbed to solid matters in Sake mash.