PURPOSE: To easily measure and process the amount of the side slip S of a vehicle.

CONSTITUTION: This apparatus a side slip tester 3 which outputs the data of the side slip of tyres when the vehicle runs straight, a vehicle position detecting means 6 for outputting the data of the position where the vehicle passes the side slip tester 3, a maximum value calculating means 4 for sequentially taking the amount of the side slip S while the vehicle is passing the side slip tester 3 thereby to calculate the maximum values SMAX1, SMAX2 of the amount S of the side slip, a side slip evaluating means 4 for evaluating it disqualified when the maximum values of tone amount of the side slip exceed permissible amount α, β of the side slip and outputting an NG signal, and an evaluation display means 4 for showing a disqualification display on a display device 5 corresponding to the maximum values of the amount of the side slip and tire NG signal.