To noninvasively estimate the blood pressure continuously in the common carotid artery (CCA), we obtained the distension waveform of the CCA from seven healthy volunteers and 20 hypertensive patients using radio-frequency ultrasound. Consequently, it was calibrated by the mean and diastolic pressure measured in the finger artery and compared with applanation tonometry, calibrated using the systolic and diastolic pressure in the brachial artery. The mean difference in estimating the mean blood pressure was 0.3 mm Hg (limits of agreement: -11.7 to 12.3 mm Hg). In estimating the systolic blood pressure, the mean difference was 8.0 mm Hg (limits of agreement: -29.8 to 45.8 mm Hg) and showed increasing variation with blood pressure. The systolic blood pressure values can be expected between 0.83 and 1.35 times the control method. In this study, we obtained proof-of-principle for noninvasively measuring blood pressure in the CCA using continuous finger blood pressure monitoring. This opens the way to estimating location specific arterial stiffness and intra-plaque elasticity.