Blood pressure values measured in four limbs are plotted on first to fourth linear axes which extend from an origin in an upper right direction, an upper left direction, a lower left direction, and a lower right direction respectively, and a rectangle composed of vertices which are determined by the plotted blood pressure values is illustrated to present the blood pressure values. This allows a specific measured value in each site to be easily known, and the relationships between the blood pressure values in the four limbs are intuitively understood from the shape of the rectangle.