Abstract: An ultrasound diagnostic device to which an ultrasound probe is connectable, measuring an IMT of a vascular wall in a carotid artery, including: a transmission unit supplying a transmission signal to the probe for causing ultrasound transmission along a longitudinal cross-section of the carotid artery; a reception unit receiving a signal based on a reflected ultrasound received by the probe, and generating a reception signal; a vascular feature calculation unit extracting position information from the reception signal, including at least one of: piece positions for vascular wall pieces; and a relative relationship between piece positions, and detecting a boundary between a CCA and a CCA bulb according to variation in the position information with respect to the longitudinal direction of the carotid artery; a ROI determination unit determining a ROI defining an IMT measurement range with respect to the boundary; and an IMT measurement unit measuring the IMT.