To provide a blood pressure estimation device capable of estimating a blood pressure at real time, and continuously and unrestrictedly.SOLUTION: A blood pressure estimation device 100 analyzes a biological signal collected from a back side of a person, then captures vibration (vibration in a living body) in a living body generated by blood flow variation from a ventricular filling period to an isovolumetric contraction period, then captures a state (index related to fluctuation (fluctuation index)) of fluctuation of an index indicating a state of the vibration in a living body. The fluctuation index is related to a state of a person, especially, information related to blood pressure. When a person is seated on or lies on his/her back for bringing his/her back into contact with on a biological signal measurement device capable of measuring a biological signal unrestrictedly, the device being attached to any kind of a chair such as a vehicular seat, a chair for desk work, or a chair for furniture, or bedding such as a bed, a blood pressure can be estimated easily, especially, whether a blood pressure of a user is included in a region indicating a normal range blood pressure (diastolic blood pressure is less than 90 mmHg, systolic blood pressure is less than 140 mmHg) or a region indicating a high blood pressure, can be estimated.SELECTED DRAWING: Figure 2【課題】非拘束、リアルタイムかつ連続的に血圧を推定することのできる血圧推定装置を提供する。【解決手段】血圧推定装置１００は、人の背部から採取される生体信号を解析し、心室充満期から等容性収縮期の血流変動によって生じる生体内の振動（生体内振動）を捉え、生体内振動の様子を示す指標のゆらぎの様子（ゆらぎに関する指標（ゆらぎ指標））を捉える。ゆらぎ指標は、人の状態、特に、血圧に関する情報と関連性がある。乗物のシート、事務用や家具用などの各種椅子、あるいは、ベッドなどの寝具等に取り付けられた、非拘束で生体信号を測定できる生体信号測定装置に、人が着席あるいは仰臥して背部を当接すると、容易に血圧の推定、特に、正常域血圧（拡張期血圧が９０ｍｍＨｇ未満、収縮期血圧が１４０ｍｍＨｇ未満）を示す領域に含まれるか高血圧を示す領域に含まれるかを推定できる。【選択図】図２
