The object is to smoothly move the position of the viewing point of the virtual camera with existence of an object between the position of the viewing point of the virtual camera and the position of the subject avoided. A camera peripheral area that has a viewing point as its center and has the radius of R, a subject peripheral area that has a subject toward which a viewing axis of the virtual camera is aligned as its center and has the radius of r, and a camera-to-subject area formed by a circular truncated cone area therebetween are set as a camera collision in which an obstacle cannot exist. When an obstacle exists in the camera collision, the position of the viewing point is adjusted. The radius R and the radius r are adjusted each time the reference distance D is changed.