An ultrasound diagnostic apparatus includes an ultrasound probe, a reference image holding unit that holds an ultrasound image acquired by fixing the position of the ultrasound probe as a reference image, a movement vector calculation unit that calculates a movement vector between two ultrasound images, a movement vector integration unit that integrates the movement vectors from the time when the reference image is held until the current time, a deformed image generation unit that generates a deformed image in which the reference image is moved and changed on the basis of an integration result, a tomographic plane determination unit that compares the deformed image with the current ultrasound image, to determine whether or not tomographic planes of the reference image and the current ultrasound image are the same as each other, and a determination result notification unit that notifies a user of a determination result.