An object recognition system including a radar, an image sensor and a controller is provided. The radar determines the position of an object, and the image sensor captures an image of the object. The controller sets a processing area within the image captured by the image sensor based on the position of the object determined by the radar and a predetermined size for the object to be recognized. The controller extracts horizontal and vertical edges from the processing area, and preferably judges whether each of the extracted edges belongs to the object based on characteristics of the object to be recognized. The controller then recognizes the outline of the object based on the edges judged to belong to the object. The object can be recognized by determining upper, lower, left and right ends of the object. On the other hand, the controller recognizes lane lines defining the lane in which the vehicle mounting the system of the invention is running. Thus, the relative position of the object to the lane lines is determined by comparing the intersections between a horizontal line corresponding to the lower end of the object and the lane lines with the left and right ends of the object.