A method and apparatus allows a user to input a tentative destination which is proximate to an intended destination when the address data for the intended destination is not found in the map database. The method includes the steps of allowing a user to specifying an intended destination in the navigation system and searching address data for the intended destination, notifying the user that the address data is not found in the map database, selecting a method for inputting data indicating a tentative destination which is considered proximate to the intended destination, allowing the user to specify the tentative destination through the selected input method, and determining a location of the tentative destination and detecting address data indicating the location of the tentative destination.