An ultrasound diagnostic apparatus according to the exemplary embodiments of the present disclosure includes: a three-dimensional data generation unit which generates three-dimensional data for each region in the body of a subject based on reflected waves reflecting back from the body of the subject after ultrasound waves have been transmitted towards the body of the subject a measurement image selection unit which respectively selects, for each region, one of the two-dimensional cross-sections that compose the three-dimensional data, as a measurement reference image used for measuring a length of each region in the body of the subject a measurement calculation unit which measures a length of each region in the body of the subject using the respectively selected measurement reference image, and calculates an estimated weight of the subject using the measured lengths and a display unit which outputs the estimated weight thus calculated.
