PURPOSE: To automatically discriminate a car family with a simple and inexppensive constitution.

CONSTITUTION: Ultrasonic distance sensors 1a, 1b, 1c detect height of a vehicle 12 and magnetic sensors 2a, 2b, 2c detect passing time of the vehicle 12, while a data processing device 4, based on their detection signals a1, b1, c1, 2, b2, c2, finds data expressing profiles of respective portions of the vehicle 12 (length and height of a hood 12a and the like). These data are compared and combined with previously stored data expressing the profiles of respective portions of respective vehicle families so as to discriminate the car family of the vehicle 12.