An ultrasound image is displayed while clarifying a positional relationship with an ultrasound probe. An ultrasound diagnostic device is provided with an ultrasound probe, a first position detecting means for detecting a position of the ultrasound probe, an ultrasound image generating means for generating an ultrasound image by using a reflected echo signal, an ultrasound volume data generating means for generating three-dimensional ultrasound volume data by accumulating the ultrasound images, a reference image generating means for generating a ultrasound reference image of an arbitrary cross section by using the ultrasound volume data and displaying an ultrasound probe mark indicating the position of the ultrasound probe in a superimposed manner on a position in the ultrasound reference image, the position corresponding to the ultrasound probe position detected by the first position detecting means, and a display means for displaying the ultrasound image and the ultrasound reference image.
