An ultrasound diagnostic apparatus includes an ultrasound image producer which produces an ultrasound image from reception data based on a predetermined set sound speed, a reception data image producer which produces a reception data image representing a luminance image of an ultrasonic echo wavefront from the reception data corresponding to a predetermined range on at least one scan line in the ultrasound image, a sound speed determination unit configured to determine an optimum sound speed based on ultrasound images respectively produced by the ultrasound image producer while changing the predetermined set sound speed, and a controller which makes an ultrasound image for diagnosis produced by the ultrasound image producer and the reception data image produced by the reception data image producer be displayed simultaneously on a display unit based on the optimum sound speed determined by the sound speed determination unit.
