An ultrasound diagnostic apparatus includes a region of interest setting unit for setting a region of interest containing at least part of a liver and at least part of a kidney in a B mode image, a controller for transmitting and receiving ultrasonic beams to obtain reception data for measuring a sound speed, a sound speed map producer for producing a sound speed map of a liver region based on the reception data for measuring a sound speed, and a hepatorenal contrast calculator for calculating an average luminance in the liver region and an average luminance in a kidney region of the region of interest and calculating a hepatorenal contrast based on the calculated average luminances.
