Wheels of a two-wheeled motor vehicle are supported by support rollers corresponding to each wheel, respectively, and an antilock brake system is operated for each wheel. Measuring means 20 and 31 measure values related to the rotation speed of rollers supporting the wheel for which the antilock brake system operates. Based on the values obtained by the measuring means 20 and 31, the waveform accompanying the change in rotation speed of the wheel that occurs by the operation of the antilock brake system is computed by a computing means 44 based on the values obtained by the measuring means 20 and 31. A determination means 45 determines whether or not a portion of the waveform obtained by the computing means 44 falls within a predetermined range or not. According to the present brake system test of a two-wheeled motor vehicle, not only is it possible to specify the malfunctioning portion easily, but it is also possible to reduce the time required for each test of the motor vehicle dramatically, enabling the test of the two-wheeled motor vehicle to be performed with high accuracy and efficiency.