The parametric motor has many excellent features as compared with the ordinary motor, and is anticipated to have practical applications. Because of several nonlinear phenomena, however, the motor operation is complex. To take the motor practically useful, we investigated the stability of the parametric oscillation and the design method of the motor. Methods of improving the characteristics of the parametric motor were discussed. We determined the dimensions and material of the stator to stabilize the parametric oscillation, and found the optimum distribution ratio of the magnetic flux in the stator used for parametric oscillation to the flux used for the motor operation.