To provide an image forming device which can convert an image which is seen from a virtual camera into a real picture with a little processing load and an information storing medium.

When a virtual camera 30 rotates around its X-, Y-, or Z-axis or moves for tracking a moving body 20 moving along a course, fluctuation is given to the camera 30 so as to express camera shake (rotational blurring). The fluctuation given to the camera 30 is decided in accordance with the rotational angular velocity or speed of the camera 30. Such a fluctuation range that becomes wider as the rotational angular velocity or speed of the camera 30 increases is found and the fluctuation contained in the range is given to the camera 30. When the rotational angular velocity or speed of the camera 30 is high, the fluctuation is limited to a limit value. The offset value between the position of the moving body 20 and the position of the steadily gazing point of the camera 30 is variably controlled based on the distance from the moving body 20 or the speed of the body 20 or registered in connection with a course block.