An image in which an enemy moving in the game space of a gun game is acquired from a movable camera viewpoint in the space is generated. A control means (steps S24 and S27-S31) which controls the movement of the camera viewpoint by using the positional relation between a viewed point determined in relation to the enemy and the line of sight of the present camera viewpoint for every image frame is provided. The means judges the specific moving state of the camera viewpoint, moves the camera viewpoint while the line of sight is fixed, calculates the angle between the direction from the camera viewpoint toward the viewed point and the direction of the line of sight of the camera viewpoint before it is moved, and turns the camera viewpoint to the viewed point in accordance with the calculated angle.