PROBLEM TO BE SOLVED: To provide data which can make a user judge the reliability of the individual measured value led out of a blood pressure measuring instrument.SOLUTION: The blood pressure measuring instrument is equipped with a cuff for oppressing a blood pressure measuring region, a pressure control means for increasing and decreasing the pressure in the cuff, a pressure sensor for detecting the pressure in the cuff, a pulse wave signal detecting means for extracting the time series data of the pulse wave signal superposed on the pressure in the cuff detected by the pressure sensor in the process of increasing or decreasing the pressure in the cuff by the pressure control means, a relational expression deriving means for deriving the relational expression between pulse wave amplitude and inner and outer pressure difference of a blood vessel on the basis of a change in a plurality of the one-cycle pulse wave signals contained in the data during a period, when at least the cuff pressure is larger than a systolic blood pressure value, in the time series data of the extracted pulse wave signal, and a degree-of-variation deriving means for deriving the degree of variation of blood pressure on the basis of the pressure value corresponding to the difference between the pulse wave amplitude in the extracted pulse wave signal and the pulse wave amplitude derived from the relational expression.COPYRIGHT: (C)2009,JPO&INPIT【課題】血圧測定装置により導出された個々の測定値の信頼性を判断可能な情報をユーザに提供する。【解決手段】血圧測定装置において、血圧測定部位を圧迫するためのカフと、前記カフ内を加圧または減圧する圧力制御手段と、前記カフ内の圧力を検出する圧力センサと、前記圧力制御手段により前記カフを加圧または減圧する過程において、前記圧力センサにより検出されるカフ内の圧力に重畳した脈波信号の時系列データを抽出する脈波信号抽出手段と、抽出された脈波信号の時系列データのうち、少なくともカフ圧力が収縮期血圧値より大きい期間のデータに含まれる複数の1周期脈波信号の変化に基づいて、脈波振幅と血管内外圧差との関係式を導出する関係式導出手段と、抽出された脈波信号における脈波振幅と前記関係式に基づいて導出される脈波振幅との差分に相当する圧力値に基づいて血圧変動量を導出する変動量導出手段と、を備える。【選択図】図7
