When rendering individual 3D models arranged in a virtual game space, normal rendering is performed without performing toon shading. Then, after rendering of all the 3D models has been completed, toon processing is performed on the rendered image data stored in a color buffer, so as to obtain a well-defined transition between light and dark. By this, the process of displaying a 3D model in an animated format arranged in the virtual game space is simplified and the processing load is reduced.