System and method of communication for navigation system and route guidance information transmitting apparatus

A communication navigation system (S) includes a server (SV) that transmits items of route guidance information to each of terminal units (T) via the Internet (IN), a processing subsystem (10), provided in each terminal unit (T), for determining whether or not the items of route guidance information from the server (SV) are necessary, a display subsystem (13) for performing guidance using only one or more items of route guidance information determined to be necessary by the processing subsystem (10), and a speech output subsystem (14).