In order to determine the blood pressure with high accuracy, the blood pressure determination device of the present invention determines the blood pressure based on the pressure signal in a specific period and the pulse wave signal measured due to the pressure related to the pressure signal in a specific period, Pulse wave calculating means for calculating a plurality of timings at which the signal satisfies a predetermined condition, a period representing a difference between the timings, and a pressure value of the pressure signal in the period, and calculating pulse wave information correlating the period and the pressure value； Data extraction means for extracting a specific data range from the pulse wave information based on the arterial viscoelasticity index and blood pressure determination means for determining the diastolic blood pressure from the correspondence relationship between the pressure value and the period in the data range.高精度に血圧を判定するために、本発明の血圧判定装置は、特定の期間における圧力信号と、特定の期間において圧力信号に係る圧力に起因して測定される脈波信号に基づき、脈波信号が所定の条件を満たす複数のタイミングと、タイミングの差分を表す期間と、期間における圧力信号の圧力値とを算出し、期間と圧力値を関連づける脈波情報を算出する脈波算出手段と、動脈粘弾性指標に基づいて脈波情報から特定のデータ範囲を抽出するデータ抽出手段と、データ範囲における圧力値および期間の対応関係から拡張期血圧を判定する血圧判定手段と、を備える。
