1. A method for searching a polygon object for a navigation system when polygon objects are not associated with points of interest (POIs) in a map database of the navigation system, comprising the following steps of: creating a data table which arranges information on the polygon objects in the map database based on polygon names; creating a data table which arranges information on the polygon objects in the map database based on polygon locations; prompting a user to specify a desired polygon object through a screen of the navigation system either by a polygon name or a polygon location; retrieving candidate polygon objects from the corresponding data tables that match inputs specified by the user and display a list of the retrieved polygon objects in a predetermined order; and allowing the user to finalize selection of the desired polygon object.