Stepping motor is one of the most serious disturbance sources which generate high-frequency vibration and deteriorate pointing stability of satellite. Those disturbance sources need to be under control of satellite system design. To control disturbance sources in system design and meet pointing stability requirements, we need both of a high-frequency vibrations control method and accurate mathematical disturbance models. For this reason, we tested a stepping motor and evaluated the data of driving disturbance vibrations and identified 'stepping motor mathematical disturbance model'. Consequently, we realized an accurate mathematical disturbance model of stepping motor which includes flexible structure as inertial load. This mathematical model can be applied to all stepping motors in which key parameters like stepping motor characteristics and inertial load's structural characteristics are given.