A blood pressure information measurement device, including first and second fluid bags in the first fluid bag； a pressure mechanism increases/decreases pressure in an internal space of the first fluid bag and the pressure in the internal space of the second bag； a control unit controls operation of the pressure mechanism； a pressure detection device detects an internal pressure of the first and the second fluid bag； and a calculation unit that calculates blood pressure information detected by the device. In calculating blood pressure information, the control unit controls operation of the pressure increase/reduction mechanism after the internal space of one fluid bag of the first and second fluid bags pressurized and expanded until internal pressure of one fluid bag reaches a predetermined pressure, the internal space of the other fluid bag of the first and second fluid bags pressurized and expanded while the one bag is kept sealed.
