A map data update method for updating nationwide updated version map data using route-specific update data is disclosed. This method has a step of creating route-specific update data, comprising update data for all routes which have been newly opened since the time of release of the nationwide updated version map data; a step of storing a plurality of route-specific update data sets with different creation dates; a step of, when updating the nationwide updated version map data of the time of release stored in a navigation apparatus in use of a prescribed first route-specific update data which has been stored, storing pre-update map files necessary to restore the nationwide updated version map data; and a step of using the first route-specific update data to update the nationwide updated version map data.