The objects of this invention are to prevent or ameliorate hypertension to improve physical constitution and finally to provide feeds, drinks, foods, health food supplements and pharmaceuticals which may be led to the prophylaxis or amelioration of life style related diseases.A prophylactic or ameliorating agent of hypertension comprising conjugated fatty acids (e.g., conjugated linoleic acid) as effective ingredients.A feed, food and drink, and health food supplement comprising the conjugated fatty acids described above.A pharmaceutical comprising the conjugated fatty acids described above.A method for prophylactic or ameliorating of hypertension in a mammal, which comprises administering to the mammal an effective amount of a conjugated fatty acid for preventing or ameliorating of hypertension in the mammal.Use of a conjugated fatty acid for preparing a pharmaceutical for prophylactic or ameliorating of hypertension.