In an ultrasonic blood pressure measurement apparatus that measures a blood pressure by transmitting an ultrasonic wave toward a blood vessel and receiving a reflected wave, a storage unit stores a β blood-pressure calculation expression that is a first relationship between a vascular diameter of the blood vessel and a blood pressure a pulse wave velocity calculation unit measures a pulse wave velocity of the blood vessel a β blood-pressure calculation expression modifying unit calculates a modified β blood-pressure calculation expression that is a third relationship obtained by modifying the β blood-pressure calculation expression using the pulse wave velocity a vascular diameter measurement unit configured to measure the vascular diameter of the blood vessel using the ultrasonic wave and a temporary blood pressure calculation unit determines the blood pressure according to the modified β blood-pressure calculation expression.
