1. A car navigation apparatus comprising: a current position detection device that detects a current position of a vehicle; and a control device that detects a plurality of roads as candidates used for map matching based upon roadmap information containing road data used for navigation of the vehicle and the current position detected by the current position detection device, and execute the map matching with a most appropriate road among the plurality of roads, the map matching being executed for a current position display of the vehicle, wherein: the control device makes a decision as to whether or not a road among the plurality of roads as the candidates used for the map matching forms a circular crossroad and does not execute the map matching when a road among the plurality of roads used as the candidates used for the map matching is judged to form a circular crossroad.