Riding on an electric skateboard needs rider's skill because it is difficult to keep standing. We should study how to move the skateboard to aid the postural control of human standing. To examine it theoretically, it requires a model of the human body and the system parameters. The purpose of this study is to estimate the postural control parameters of the model precisely when some disturbances act on the support surface. The structure of the model is regarded as a simple rigid-body and the torque for the postural control is assumed to be generated by muscle groups. We assume that the torque is determined by delayed feedback in terms of the angle and the angular velocity of the body. To estimate the feedback gains and the delay time of the postural control, we implemented impulse response tests. Center of mass (COM) and center of pressure (COP) were measured by motion capture and load measuring devices respectively. In this study, we propose a method which compares characteristic equations to estimate the postural control parameters. While variations in the estimated parameters generally appears, the presented method enables us to reduce the variations. The estimated parameters indicated that the parameters do not vary according to amplitude of the impulse. The validity of the estimated parameters were verified by comparing the equation of motion and experimental results.