1. A map update data supply device that is connectable to a navigation device that includes a map database via a communication network, the map update supply device being configured to supply data for updating the map database to the navigation device, the map database including at least road network information and being divided into a plurality of sections, the map update data supply device comprising: a storage device including an update map database configured to manage versions of an update data file for updating a difference in the map database for each of the sections, and store the update data file of each of the versions for each of the sections; and a control device including a request update data extraction unit configured to, based on an update request from the navigation device, extract a request update section that is a section for updating the difference, and extract, for each request update section, the update data file of up to a latest version, a safeguard update data extraction unit configured to, if all request update sections are updated up to the latest version, extract a safeguard update section that is a section needed to be updated to ensure a road network connection between adjacent sections, and extract, for each safeguard update section, the update data file of up to an update safeguard version that is a version needed to be updated to ensure the road network connection, an integrated data generation unit configured to generate a request update integrated data file for a single time of difference update by integrating, for each request update section, all versions up to the latest version of the update data file for each request update section extracted by the request update data extraction unit, and generate a safeguard update integrated data file for a single time of difference update by integrating, for each safeguard update section, the update data file up to the update safeguard version for each safeguard update section extracted by the safeguard update data extraction unit, and an integrated data supply unit configured to supply, to the navigation device, the request update integrated data file and the safeguard update integrated data file generated by the integrated data extraction unit.