In the present invention, when a 3D medical image is displayed on a 3D display, the position of accompanying information displayed at the same time is appropriately controlled. The position of the accompanying information in the coordinate system of a 3D signal value that is an item to be drawn is computed, and said position is saved in a storage unit. By integrating a 3D data area and an accompanying information area, a drawing process unit generates an output image to be displayed in a display unit, said 3D data area being drawn for an area specified by mask information that specifies an area to be drawn among an array of the 3D signal value that is the item to be drawn, and being drawn on the basis of information that specifies a drawing method for a 2D image based on the 3D signal value array, and said accompanying information area being drawn for the accompanying information, which is associated with the item to be drawn, and being drawn on the basis of position information for the accompanying information determined by a drawing control unit. The display unit displays the drawn output image.