1. A vehicle detecting method, comprising: creating, by a controller, a disparity map using images photographed by a stereoscopic imaging device; detecting, by the controller, a road area on the disparity map; detecting, by the controller, a vehicle present in the road area in a shape of a stereoscopic object; converting, by the controller, the disparity map into a top view image; detecting, by the controller, a vehicle area having a rectangular shape in the top view image; converting, by the controller, the top view image into a second disparity map; and detecting, by the controller, a height of the vehicle area the second disparity map.