To provide a vehicle testing device capable of measuring accurately and surely braking forces of right and left wheels constituting the vehicle.

A pair of front-and-rear testing rollers 3, 3 journaled on right and left upper faces of a device body 2 constituting this vehicle testing device 1 are rotated integrally by a driving force of a driving device 4. When a driving force from the vehicle side works on the testing roller 3 at the braking test time, a braking force (for example, torsion or strain) generated in a detection shaft 15 for connecting the rear testing rollers 3, 3 is electrically detected by braking force detectors 6a, 6a constituting a braking force detection device 6, and operation processing of a detection signal outputted from the braking force detector 6a is performed by a detection information processing device 26 incorporated in an indicating device 23, and the result is displayed and recorded as the braking forces of right and left tires A.