A high-accuracy blood pressure value deriving method that is hardly influenced by individual differences of a person to be measured is provided. A blood pressure measuring apparatus includes a cuff member comprising a compression air bladder, a sub air bladder, and a pulse wave detection air bladder, pressure control means for pressurizing or depressurizing each air bladder, a pressure sensor which senses the internal pressure of each air bladder, pulse wave signal extracting means for extracting time-series data of a pulse wave signal superposed on a cuff internal pressure, in the process during which the pressure control means pressurizes or depressurizes each air bladder, and blood pressure value deriving means for deriving a systolic blood pressure value and/or a diastolic blood pressure value based on a change in feature amount of the pulse wave signal and a cuff internal pressure at a point of time of the change.
