An ultrasound diagnostic apparatus according to an embodiment includes a processing circuitry. The processing circuitry acquires first image data that is image data obtained during the ultrasound scan executed on the object and that is image data before the coordinate conversion corresponding to the format of the ultrasound scan. The processing circuitry uses the trained model generated through the learning using the first image data obtained during the previously executed ultrasound scan and the area including the object in the first image data to estimate the area in the acquired first image data.