A video game machine includes a monitor which permits three-dimensional viewing, a virtual camera controller which selectively provides on-screen presentation in 2D display mode in which two virtual cameras for capturing images are matched with each other and in 3D display mode in which the two virtual cameras are set to achieve a prescribed distance therebetween, an image display controller which generates a 3D image presented on the monitor from image data acquired by the two virtual cameras, a display mode switching processor which repositions the two virtual cameras from the positional relationship in one display mode to the positional relationship in the other in a stepwise fashion. Switching between the 2D and 3D display modes is smoothened and stimulation of a player's eyes or brain caused by a sudden change between states with or without stereoscopic effect is suppressed.