To display 3D image data more realistically.

A CPU 101 of this game device selects object data positioned in the visual field set based on the position of a player's visual point among the object data stored in the main memory 104. The selected object data are converted in perspective to the image data to be a projected image on the visual screen. Then the CPU 101 Z-sorts the converted image data, and extracts the data which are more than a prescribed distance away from the position of the visual point among the Z-sorted image data to produce translucent dummy polygons with a translucent image shifted by a few dots as a texture. The GPU 109 draws an unclear and dim image based on the image data including the translucent dummy polygons produced by the CPU 101.