In the conventional 3-dimensional image display, it is impossible to simultaneously and symmetrically display right and left side of a patient and accordingly, it is impossible to effectively use the medical 3-dimensional image information by comparing and evaluating the right and left symmetric portions when performing a diagnosis or planning surgery and curing. Provided is a display control program enabling a medical 3-dimensional image displayed on the display screen in a pair of right and left display and rotation of the pair of right and left display around a vertical axis (Z axis) in the reverse direction so as to create an image of the opposite side corresponding to one point-of-view direction, thereby simultaneously and symmetrically displaying the right and left sides of the patient. Furthermore, in this program, when a cross section is specified for one of the right and left of the 3-dimensional image, a cross section at the symmetric position of the other image is automatically displayed so as to simultaneously and symmetrically display the right and the left side of the patient.