A map data updating system is basically provided with a map distribution system and at least one map data updating device. The map distribution system includes a map data generating section and an information distributing section. The map data updating device is configured to process the distribution map data from the map distribution system, and includes a map data updating determining section and an update map data requesting section. The map data generating section configured to generate distribution map data including at least one target map data unit of a map that has been divided into a plurality of map units, with the distribution map data including map data version information for a target map unit to be updated and at least one perimeter map unit existing along a perimeter of the target map unit to be updated. The information distributing section configured to electronically distribute the distribution map data. The map data updating determining section configured to determine whether to update previously stored map data corresponding to the target map unit based on the map data version information included with the distribution map data. The update map data requesting section configured to send an update map data delivery request to the information distributing section when the map data updating determining section determines previously stored map data version information of the map data updating device relating to the at least one perimeter map unit does not match the map data version information included with the distribution map data.