This study focuses on the stabilizing operation of a pendulum by using myoelectricity as the control signal. Recently myoelectricity is highlighted in the control application fields such as artificial hands and powered suits. However, even expert operators fail in stabilization of the pendulum because controlling of the target system by using myoelectricity is a difficult task. To deal with such a situation, introducing of an operation assistance by an automatic control is one of useful solutions, however, in general, the design of such automatic control system requires the model of myoelectricity. Thus it is still challenging task to achieve modeling and identification of myoelectricity. This paper tries to make a model of the dynamical system of the myoelectricity by utilizing the nonlinear ARX models proposed by Furuta and verifies the effectiveness of the model through some experiments.