A navigation system is designed to scale a map image such that a redrawn map image shows an icon of the most relevant object at a center of a cursor when the scale of the map image is changed so that the user will not lose sight of the most relevant object such as an icon showing a destination. The navigation system prioritizes an icon representing a particular object based on a predetermined priority order and changes the position of the map image so that the icon of the highest priority comes to the center of the cursor when the map scale is changed. Thus, the icon of the highest priority always remains at the center of the cursor, thereby preventing from loosing the sight of the icon of the highest priority when zooming in the map image.