Ultrasound diagnostic apparatus that receives a reception signal representing the reflection waves from ultrasound probe, includes position specifying section that specifies the depth of detection object inside the subject based on the temporal variation of the reception signal, and position specifying section that specifies the position of detection object in the first direction based on the reception signal generated based on the reflection waves from detection object obtained with the ultrasound beams transmitted at a first angle and a second angle which are different from each other in a transmission direction of the ultrasound beam.