Recently, global warming is the serious world problem. To solve this issue, many new vehicles appear today. For example, there is electric motorcycle (EM). In the almost conventional approaches, one inverted pendulum model for camber angle is used. This model does not include the rider motion and it is not good enough to consider stabilization of vehicle in the real world. So, this paper proposes a new EM system with assistant pendulum. Also, the proposed human camber angle disturbance observer (HDOB) considers compensation for stabilization of human camber angle. By these proposed approaches, the improvement of posture stabilization of whole electric motorcycle system considering rider motion is validated by the simulations.