A metabolic syndrome relieving agent that is free from a problem of side effects and can be taken for a long term is provided. Bergamottin is used as an agent for relieving a metabolic syndrome. Since bergamottin has functions of activating PPAR.alpha. and PPAR.gamma., promoting the secretion of adiponectin in adipocytes and inhibiting the generation of VLDLs in hepatic cells, it is possible to prevent or treat diseases such as insulin resistance, hyperinsulinism, type 2 diabetes, obesity, visceral fat obesity, hypertension, hyperlipemia, arteriosclerosis and the like and thus prevent or treat the metabolic syndrome. Also, as understood from the fact that citrus fruits such as a grapefruit or the like containing bergamottin have been eaten for many years, they have no problems in terms of safety and have a low calorie content, and therefore, they can be taken for a long term. Further, since bergamottin is tasteless and odorless, it does not impair the unique taste of a food when added to this food, so that it can be added to foods and taken.