and image 158 is the projected image of slice 105 an image group 154 a group of images of slices projected on the plane that intersects perpendicularly with the plane defined by the biopsy needle 107 and y axis and includes y axis in fig2 image 159 is the projected image of slice 102 image 160 is the projected image of slice 103 image 161 is the projected image of slice 104 and image 162 is the projected image of slice 105 by projecting images on two planes that intersect perpendicularly the motion of a biopsy needle may be observed more accurately on the image a guideline 171 172 is displayed between the insertion point of a biopsy needle on the surface of a subject and the region of interest and operation of the biopsy needle is made easy the x direction display control box 135 and z direction display control box 136 and the display direction of images can be set up initially as shown in display format 61 as shown in display format 62 changing the x direction display control box 135 and the z direction display control box 136 changes the display direction 0052 fig2 illustrates display formats 63 and 64 in which image display areas are overlapped and displayed on a three dimensional image with a different opacity in display format 63 and display format 64 an image group 163 is group of images of slices projected on the plane defined by the biopsy needle 107 and y axis as illustrated in fig2 image 165 is the projected image of slice 102 image 166 is the projected image of slice 103 image 167 is the projected image of slice 104 and image 168 is the.