An ultrasound diagnostic apparatus includes: an ultrasound transducer (12) including two-dimensionally arranged vibration elements a beam former (23) that drives the ultrasound transducer (12) to perform three-dimensional scanning and that acquires ultrasound data of a three-dimensional space a delay calculating circuit (24) sets scan conditions of the beam former (23) a graphic circuit (27) that generates an ultrasound slice image of a predetermined cut surface from the ultrasound data of the three-dimensional space and a CPU (29) that causes the delay calculating circuit (24) to change the scan conditions according to the cut surface set at a desired position.
