The ultrasound diagnostic apparatus acquires an ultrasound image for examining an inspection object using an ultrasonic beam, and includes a sound velocity determiner configured to determine a sound velocity in the inspection object, and a sound velocity searching range setting section configured to set a range in which a sound velocity is searched by the sound velocity determiner. The sound velocity searching range setting section sets a sound velocity searching range using a sound velocity calculated in a predetermined range with respect to at least one of space and time.
