Map data product, map data processing program product, map data processing method, and map data processing device

A first data product that can be read into a computer or a map data processing apparatus, contains therein map data having map-related information of a map. The map data includes: a structure having the map-related information divided into units of a plurality of divisions into which the map is divided; and a structure having management information for the map-related information divided into units of the divisions, and: the map-related information obtained by the computer or the map data processing apparatus can be updated in units of the individual divisions by using the management information.