An ultrasound image is displayed while clarifying a positional relationship with an ultrasound probe. An ultrasound diagnostic device 10 is provided with an ultrasound probe 2, a first position detecting means 4, 5 for detecting a position of the ultrasound probe 2, an ultrasound image generating means 6 for generating an ultrasound image by using a reflected echo signal, an ultrasound volume data generating means 9 for generating three-dimensional ultrasound volume data by accumulating the ultrasound images, a reference image generating means 12 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 15 for displaying the ultrasound image and the ultrasound reference image.
