1. A method for determining an object type of a reflective object on a track, comprising: a reflective point detecting step of detecting a plurality of reflective point in front of one's vehicle in a traveling direction; a first detecting step of grouping the plurality of reflective points detected in the reflective point detecting step by a predetermined standard and regarding the grouped reflective points as detection objects; a relative speed measuring step of measuring relative speeds of the detection objects detected by the first detecting step with respect to one's vehicle; and a first determining step of determining types of the detection objects based on the relative speeds detected in the relative speed measuring step.