For generating ultrasonic projection images in which various kind of ultrasonic projection images have been appropriately combined, the invention is provided with: a storage unit that stores tomographic image volume data and elastic image volume data； a volume rendering unit that generates tomographic projection images by volume rendering on the basis of the tomographic image volume data； a display device that displays the ultrasonic projection images generated by the volume rendering unit； and an operation unit for inputting commands to control the volume rendering unit. For one of the rendering spaces partitioned by a cutting plane set in the rendering space by a command input from the operation unit, the volume rendering unit renders voxels of tomographic image volume data corresponding to the voxels of elastic image volume data that have elasticity values satisfying a set threshold value, and generates and displays the tomographic projection image on the display device.
