An arterial-wall stiffness evaluation system of the present invention includes: a cuff to be attached to a part of a living body； a pressure sensor for detecting pressure in the cuff； a cuff-pressure control section for controlling the pressure in the cuff to be increased or decreased up to a predetermined value, based on a value detected by the pressure sensor； and a data processing section for calculating, based on pulse waves detected by the pressure sensor, pulse-wave amplitudes of cuff-pressure pulse waves and blood-pressure pulse waves, and for evaluating arterial-wall stiffness based on the pulse-wave amplitudes. The arterial-wall stiffness is evaluated by a pressure-diameter characteristic curve, which represents a relationship between vascular diameter and transmural pressure applied to a vascular wall, or by estimation from shapes and amplitudes of the detected pulse waves. Alternatively, the evaluation is performed by estimating, from the detected pulse waves, a differential function obtainable by differentiating a pressure-diameter characteristic curve with respect to a transmural pressure, or by use of an arctan or a sigmoid function. This allows anybody to easily evaluate blood vessel stiffness anytime with high accuracy even at home without any special knowledge.
