1. A driver assistance method, comprising: sensing, by a controller, whether a vehicle enters a slope road; detecting, by the controller, information of the slope road using sensors which are equipped in the vehicle; confirming, by the controller, whether the slope road is a curved road based on the information of the slope road; measuring, by the controller, a curvature of the slope road when the slope road is confirmed to be a curved road; and controlling, by the controller, a steering apparatus of the vehicle based on the curvature of the slope road, wherein the measuring of the curvature of the slope road includes: calculating, by the controller, a slope of left and right boundary lines of the slope road; detecting, by the controller, a gradient using the slope of the boundary; and calculating, by the controller, the curvature of the slope road using the gradient.