It is provided a blood vessel function inspecting apparatus including: a blood vessel diameter measuring portion configured to measure a diameter of a blood vessel; a blood vessel wall thickness measuring portion configured to measure a wall thickness of the blood vessel; and a blood vessel function index value calculating portion configured to calculate a function index value for diagnosing the blood vessel of its function, after releasing of the blood vessel from blood flow obstruction, by dividing an amount of dilatation of said diameter of the blood vessel continuously measured by said blood vessel diameter measuring portion, by the wall thickness measured by said blood vessel wall thickness measuring portion.