An ultrasonic diagnostic apparatus including a multi-thresholding unit that performs multi-thresholding on the volume data of the blood flow speed on the basis of a reference value related to the blood flow speed. A surface extraction unit extracts a surface of the blood flow on the basis of the multi-threshold volume data. A weighting unit performs a weighting used for calculating the position of the center of gravity for the blood flow region formed by the blood flow surface. A center of gravity position calculation unit calculates a position of the center of gravity of the blood flow region. The Doppler sample marker position setting unit sets the position of the Doppler sample marker to the position of the center of gravity for the blood flow region. A Doppler sample marker movement control unit controls movement of the Doppler sample marker on the basis of the Doppler sample marker position setting data.
