When a user turns on an ignition switch at a parking lot so as to restart travel to a destination, a navigation system computes a distance from the parking lot to an intermediate position included in a guide route currently designated. When the computed distance is within a predetermined distance, whether the user has visited the intermediate position or not is inquired of the user. When the user inputs that the intermediate position has been visited, the navigation system re-designates a new guide route to the destination without need to pass by the intermediate position.