Disclosed is a flavonoid bioabsorption-promoting composition or food/beverage which can improve the bioabsorption of quercetin or other flavonoids having antioxidant effect and therefore are expected to be effective for the prevention of various diseases. It is found that ingestion of apple pectin can improve the bioabsorption of quercetin and other flavonoids by about 2 times and shows higher physiological activity compared to the case where apple pectin is not ingested. Based on this finding, a flavonoid bioabsorption-promoting composition or food/beverage can be provided, which contains apple pectin as an active ingredient and therefore can improve the bioabsorbability of a flavonoid and show a flavonoid bioabsorption-promoting activity. By using apple pectin or a food additive containing apple pectin, it becomes possible to provide a food or beverage which contains quercetin or other flavonoids, which are popularly ingested and which are classified in to a category of a processed food including a soft drink, supplement, seasoning, confectionery, and a prepared meal.