An ultrasound diagnostic apparatus according to one embodiment includes processing circuitry. The processing circuitry acquires local function index values related to a right ventricle. The processing circuitry generates a functional image of the right ventricle representing a distribution of the local function index values, using a medical model diagram of the right ventricle, the medical model diagram being a model diagram in which the right ventricle is developed onto a plane, and in which a blood inlet portion leading into the right ventricle and a blood outflow portion leading out from the right ventricle are plotted to positions that are separated from each other on the external circumference side of the model diagram. The processing circuitry then causes a display to display the functional image of the right ventricle.