A technique is provided for degrading a resveratrol glycoside, or degrading a resveratrol glycoside and an isoflavone glycoside, to promote the production of an aglycone(s), thereby enhancing the absorption thereof into a living body. A bacterium belonging to the genus Bifidobacterium is used as an active ingredient of an aglycone production promoter which is used for promoting the production of an aglycone(s) from a glycoside(s). The aglycone production promoter is incorporated into a pharmaceutical composition for preventing and/or treating a disease for which an aglycone(s) is/are effective, or into a food or beverage composition for producing an aglycone(s).
