This paper presents a miniature motorcycle robot developed for the purpose of research on attitude control at the time of traveling and resting a motorcycle mobile body. The miniaturization has been achieved by developing a small board using MPU and FPGA as a controller. This motorcycle mobile robot has a mechanism featuring the use of an inertial rotor in addition to the steering mechanism of a common motorcycle. The use of the inertial rotor enables the balance to be maintained even at the time of rest. Using this function of being able to maintain balance even at the time of resting, we measured the effect of a steering operation on balance and successfully compared it with the theory. Furthermore, balanced traveling is achieved by using only an inertial rotor at a low speed and only steering at high speed.