Disclosed is a lane information generating method that can generate lane information of an increasing or decreasing lane which increases or decreases from a traveling lane with high accuracy is provided. By determining characteristic points based not only on traveling trajectory information of a vehicle but also on the shape of the increasing line of the increasing lane increasing from two traveling lanes, a control unit can complementarily using information of a shape of the increasing line at a position at which variation is easily generated in the traveling trajectory, and thus generate the characteristic points as the lane information of an increasing line with high accuracy.