PROBLEM TO BE SOLVED: To propose a technique for realizing highly accurate calculation.SOLUTION: A blood pressure measurement apparatus 1 comprises: a blood vessel diameter measurement section 2 for measuring a blood vessel diameter of a measurement object blood vessel of an examinee； a pressurization blood pressure meter 5 for acquiring a blood pressure of the examinee； a calculation section 774 for calculating a correlation between the blood vessel diameter and the blood pressure on the basis of measurement results of the blood vessel diameter measurement section 2 and measurement results of the pressurization blood pressure meter 5 at a plurality of pieces of timing when blood pressure values are different from one another at the time of an artificial dialysis of the examinee； and a blood pressure calculation section 778 for calculating the blood pressure from the blood vessel diameter measured by the blood vessel diameter measurement section 2 by using the correlation subsequent to the artificial dialysis.【課題】正確性の高い算出を実現するための手法を提案すること。【解決手段】血圧計測装置１は、被検者の計測対象血管の血管径を計測する血管径計測部２と、被検者の血圧を取得する加圧血圧計５と、血圧値が異なる被検者の人工透析時の複数タイミングにおける血管径計測部２の計測結果および加圧血圧計５の計測結果に基づき血管径と血圧との相関を算出する算出部７７４と、人工透析の後、相関を用いて血管径計測部２によって計測された血管径から血圧を算出する血圧算出部７７８とを備える。【選択図】図４
