A method of cufflessly and non-invasively measuring blood pressure in a wrist region of a patient in association with a communication device that relays the information being measured. The method includes the steps of detecting a magnitude difference between a plurality of pulse wave signals detected from a wrist of a user detecting feature points from an electrocardiogram (ECG) and pulse wave signals detected from the user extracting variables needed to calculate the highest blood pressure and the lowest blood pressure using the detected feature points and calculating the highest blood pressure and the lowest blood pressure of the user by deducing a scatter diagram using the extracted variables.
