A new method for suppression of rotor oscillation in open-loop drive of a stepping motor is proposed. In this method, the torque equilibrium position of the motor is manipulated so as to guarantee the insensitiveness to the variation of rotor inertia; the motion of the equilibrium position is made to be nonoscillatory, and the frequency of the motion is bound within the region limited by the maximum frequency determined by considering the performance on the condition with the largest inertial load. The exciting sequence used for a single-step drive is tuned by using the technique of genetic algorithm. It is shown by the experimental results that rotor oscillation can be well suppressed on the load conditions with different inertial loads.