UPDATE METHOD OF MAP DATA AND MAP INFORMATION SYSTEM

In an update method of map data executed by a map information system provided in a vehicle, wherein the map data includes multiple pieces of block data separated corresponding to blocks on a map and stored in a storage device of the map information system, the map information system decides priority orders of pieces of block data to be updated based on at least one of a position of an own vehicle, a route to a destination, and a passage history, communicates with a map server having a latest version of the map data and downloads update data of the pieces of block data to be updated from the map server in accordance with the priority order, and updates the pieces of block data stored in the storage device based on the downloaded update data.