A car navigation system includes: a vehicle-information acquiring means 14 for acquiring the vehicle information held by a vehicle 2; a setting-information generating means 15, 16 for generating setting information to be set in a processing program 19 based on the vehicle information acquired by the vehicle-information acquiring means; a setting-information notification means 17 for notifying the setting information generated by the setting-information generating means 15, 16 to the processing program 19; and a setting-information switching means 18, included in the processing program 19, for switching the internal setting state of the processing program 19 according to the setting information given by the setting-information notification means, wherein the processing program 19 performs a navigation function in the setting state switched by the setting-information switching means 18.