Water-soluble isoflavone composition, process for producing the same, and use thereof

An isoflavone composition which contains an α-glucosyl isoflavone and isoflavone and optionally an isoflavone aglycone, wherein the ratio of the amount of aglycone in the isoflavone and the isoflavone aglycone in total to the amount of aglycone in the α-glucosyl isoflavone [(the amount of aglycone in α-glucosyl isoflavone)/(the amount of aglycone in isoflavone plus the amount of isoflavone aglycone)] is at least 2.5/1; a water-soluble isoflavone composition which contains an α-glucosyl isoflavone, isoflavone and isoflavone aglycone, wherein the ratio of the amount of isoflavone aglycone in the composition is 0.01 to 20% to the total amount of aglycone in the composition; and beverages, cosmetics, pharmaceuticals, or feeds, which contain any one of the above compositions.