The conventional antilock brake systems (ABS) control the braking action according to the slip ratio between the wheel and road surface. We are developing another concept of ABS which is controlled based on the wheel-to-road surface friction coefficient. In this system the wheel speed sensors are not required but the friction coefficient detectors are provided. This system controls the brake fluid pressure in such a manner that the brake will always be applied at or near the maximum friction coefficient. As the results of the examination for verification it was found that our ABS functions as ABS preventing locking up of the wheels during braking process.