The aim of this study was to identify the onuses of abnormal precipitation in buckwheat extracts and to suggest the preventive solutions. Abnormal precipitation was formed by the coagulations of small round droplets, and increased when poor quality or old buckwheat used. It was found that, unlike poor quality buckwheat, extracts made from fresh buckwheat showed almost no saccharifying enzyme activity and a lower number of microorganisms. The addition of branched starch to the extracts restricted the occurrence of abnormal precipitation and microorganisms and imparted stability to the extracts.