PURPOSE: To reduce measuring errors in a vehicle speed tester by comparing a displayed locked value of a speed meter with a predetermined value, so that the needle of the car-carrying speed meter falls upon a standard value.

CONSTITUTION: A car 11 is placed on the vehicle speed tester 1 whose rear drum 3 is turned by a command device 10. Its revolution is then transmitted to a vehicle speed calculator 4 so that the vehicle speed of the car 11 is displayed on a digital speed meter 6W9 of a speed display device. When the car-carrying speed meter displays a predetermined value by controlling the accelerator pedal, whereupon a lock switch 12 is pressed, the vehicle speeds given by the calculator 4 are lock-displayed on the corresponding indicators 7W0. Proper function of the car-carrying speed meter is evaluated by judging if the difference between the locked display value and the value displayed on the car-carrying speed meter exists within a standard value.