Even if the measurement posture is determined under the same determination conditions for the sitting position and the supine position, it is not appropriate to determine whether or not the measurement position is correct. When the blood pressure measurement device is set to the nighttime (sleep) blood pressure measurement mode in the sitting position, the supine position, and the blood pressure measurement, the position of the blood pressure measurement device in the supine position and the height of the heart position of the measurement subject are measured by the measurement posture determination unit. The measurement posture is determined in consideration of the difference between the two, and the blood pressure value is acquired.座位と仰臥位を同じ判定条件で測定姿勢を判定しても、正しい測定位置か否か判定することは適切ではない。血圧測定装置は、座位と仰臥位と血圧測定において、夜間（睡眠）血圧測定モードに設定した際に、測定姿勢判定部が仰臥位における血圧測定装置の位置と被測定者の心臓位置の高さの差を考慮した測定姿勢判定を行い、血圧値を取得する。
