A blood pressure measurement device is equipped with a pressing surface 6b which is formed with pressure sensors 6a and 7a, an air bag 2 for pressing the pressing surface 6b toward a radius artery T that runs under a skin of a living body； an air bag drive unit 11 for controlling the pressing force of the air bag 2, and a control unit 12 for calculating blood pressure values in the radius artery T on the basis of pressure pulse waves that were detected by all of the pressure sensors 6a and 7a in a process that the pressing force was increased or decreased.
