An electric device for executing a process based on a map data includes: a map data memory (13); a work memory (19c); and a CPU (19) for developing a map data from the map data memory into the work memory. The CPU executes the process based on the developed map data. The map data provides a road network defined by unit links and link connection relationships, and includes an attribution data in each link. The CPU generates a node table according to the attribution data. The node table stores a link connection information in each node as the connection point coupled with links. The link connection information provides identification of the links coupled with each other at a corresponding node. The CPU writes the node table as the developed map data into the work memory.