PURPOSE: To prevent the jumping phenomenon of a mobile object in a three- dimensional CG animation by small calculation load.

CONSTITUTION: The center of gravity of an object is defined as a calculated point and the moving vector 10 of the object on a screen is calculated from the centroid point 4 of the object 1 of the present frame and the centroid point 5 of the object 2 of the previous frame. Next, the locations of polygon vertexes composing the object 1 are evaluated based on the moving vector 10 and translucent polygon configuration vertexes 7 and 7' are selected from them. Next, a translucent polygon 11 is prepared by translucent polygon configuration vertexes 8 and 8' selected in the previous frame, an auxiliary vertex to be the middle point of these and the translucent polygon configuration vertexes 7 and 7, and this polygon is arranged within three-dimensional CG space by prescribed transparency. This translucent polygon 11 is displayed with the object on a screen. In the translucent polygon 11, transparency is increased in accordance with the progress of the frame. After a prescribed frame advances, the polygon 11 becomes completely transparent.