LANE DETERMINING DEVICE AND NAVIGATION SYSTEM

Provided is a lane determining device that is capable of quickly and accurately determining the lane traveled by a host vehicle traveling on a road with a plurality of lanes in each direction. A lane determining device that determines the lane traveled by the host vehicle traveling on a road with a plurality of lanes in each direction comprises: road geometry obtaining means that obtains road geometry; imaging means that images the road; division line recognition means that recognizes a division line from an image imaged by the imaging means; first path computation means that computes a path of the host vehicle by repeatedly computing a distance from the division line recognized by the division line recognition means to the imaging means; second path computation means that computes a path of the host vehicle based on the road geometry obtained by the road geometry obtaining means and on autonomous navigation; third path computation means that computes a path of the host vehicle based on a first path computed by the first path computation means and on a second path computed by the second path computation means; and traveled lane determination means that determines the lane traveled by the host vehicle based on a third path computed by the third path computation means.