An ultrasonic diagnosis apparatus comprising: ultrasonic image generating means for reconstructing an ultrasonic image from reflection echo signals output from an ultrasonic probe; storing means for storing volume image data pre-obtained by a diagnostic imaging apparatus; reference-image generating means for extracting tomographic image data corresponding to a scan plane of the ultrasonic wave from the volume image data stored in the storing means and reconstructing a reference image; controlling means for causing the reference image and the ultrasonic image to be displayed on a screen; and displaying means for displaying the reference image and the ultrasonic image, wherein, in accordance with the tomographic image data and a positional relationship between the ultrasonic probe and a patient, the reference-image generating means is adapted to extract tomographic image data of a portion corresponding to a view area of the ultrasonic image to generate the reference image, and wherein, of the reference image, the region corresponding to the view area is displayed with the same magnification as the ultrasonic image; the ultrasonic diagnostic apparatus further comprising a 3D body-mark determining unit for extracting a three-dimensional visualized image from the volume image data stored in the storing means and superimposing the scan plane in translucent color on the three-dimensional visualized image to be displayed on the displaying means, wherein the reference-image generating means is adapted to reconstruct the reference image of the same cross section as the scan plane of the ultrasonic image which scan plane is also superimposed on the three-dimensional visualized image; wherein characterized in that the 3D body-mark determining unit is adapted to determine a positional relationship between the scan plane and a target set on the reference image in the volume image data to cause a direction and a distance of the target relative to the scan plane to be displayed on the screen. ultrasonic image generating means for reconstructing an ultrasonic image from reflection echo signals output from an ultrasonic probe; storing means for storing volume image data pre-obtained by a diagnostic imaging apparatus; reference-image generating means for extracting tomographic image data corresponding to a scan plane of the ultrasonic wave from the volume image data stored in the storing means and reconstructing a reference image; controlling means for causing the reference image and the ultrasonic image to be displayed on a screen; and displaying means for displaying the reference image and the ultrasonic image, wherein, in accordance with the tomographic image data and a positional relationship between the ultrasonic probe and a patient, the reference-image generating means is adapted to extract tomographic image data of a portion corresponding to a view area of the ultrasonic image to generate the reference image, and wherein, of the reference image, the region corresponding to the view area is displayed with the same magnification as the ultrasonic image; the ultrasonic diagnostic apparatus further comprising a 3D body-mark determining unit for extracting a three-dimensional visualized image from the volume image data stored in the storing means and superimposing the scan plane in translucent color on the three-dimensional visualized image to be displayed on the displaying means, wherein the reference-image generating means is adapted to reconstruct the reference image of the same cross section as the scan plane of the ultrasonic image which scan plane is also superimposed on the three-dimensional visualized image; wherein characterized in that the 3D body-mark determining unit is adapted to determine a positional relationship between the scan plane and a target set on the reference image in the volume image data to cause a direction and a distance of the target relative to the scan plane to be displayed on the screen.