PURPOSE: An apparatus and a method thereof are provided to improve the accuracy of blood pressure measurement by controlling an optimal pressure fluctuation velocity of a blood vessel according to the pulse speed of a subject. CONSTITUTION: A pressure sensor(110) senses a sphygmus waves and pressure from a blood vessel of a subject. A pulse detecior(121) detects peak to peak interval from a pulse wave of a subject. An optimal pressure fluctuation velocity detector(122) detects the optimal pressure fluctuation velocity of a blood vessel by using the peak to peak interval. A pressurization unit reduces or increases the pressure of the blood vessel to the optimal pressure fluctuation velocity. A blood pressure detector(123) detects the blood pressure of a subject based on the pulse wave of a subject and the pressure of the blood vessel.
