1. A method of applying a transmission wave to a predetermined range in a width-wise direction of a subject vehicle, and recognizing objects located ahead of the subject vehicle on the basis of reflected waves which result from reflections of the transmission wave, the method comprising the steps of: calculating positions of the objects; calculating a lane-sameness probability for each of the objects that the object and the subject vehicle are on a same lane; generating object information pieces corresponding to the objects respectively, the object information pieces representing the calculated positions of the objects and the calculated lane-sameness probabilities for the objects; determining whether or not at least two objects among the objects become substantially equal in position; in cases where it is determined that at least two objects become substantially equal in position, recognizing the at least two objects as a single object; selecting one from the at least two objects which relates to a calculated lane-sameness probability equal to or higher than a predetermined value; and causing said single object to take over an object information piece corresponding to the selected object.