Patent ID: 8232900

Claim:
A navigation system mounted on a vehicle, which searches a guidance route to a destination for guiding the vehicle, comprising: a guidance route information acquiring unit configured to acquire information on the guidance route; a road information acquiring unit configured to acquire road information on roads contained in the guidance route; a guidance route determination unit configured to determine, when the guidance route is composed of a first lane and a second lane, the lanes having opposite traveling directions in a divided two-lane road and a connection road connecting the first lane and the second lane, whether the guidance route passes in the order of the first lane, the connection road, and the second lane, based on the guidance route information acquired by the guidance route information acquiring unit and the road information acquired by the road information acquiring unit; a condition determination unit configured to determine whether the connection road corresponds to an extension distance greater than a predetermined distance, if the guidance route determination unit determines which the guidance route passes in the order of the first lane, the connection road, and the second lane; a route guiding unit configured to perform and issue double-turn guidance to prompt a user to perform a double-turn, if the condition determination unit determines that the connection road corresponds to an extension distance greater than the predetermined distance; and the route guiding unit configured to perform and issue U-turn guidance to prompt a user to perform a U-turn, if the condition determination unit determines that the connection road corresponds to an extension distance less than or equal to the predetermined distance.