A novel design of a simple square-frame USM (ultrasonic motor) was proposed. The stator of the motor consists of a square-frame shape elastic body and four rectangular plate ceramics. The four ceramics were attached to outer surfaces of the square-frame elastic body. The same phase voltages were applied to the ceramics on horizontal surfaces, and 90 degree phase difference voltages were applied to the ceramics on vertical surfaces. When the four outer edges of stator were clamped, the bending vibrations of the right angled bars were transformed into travelling vibrations and elliptical displacements were generated at the center of the bars. To find an optimal size of a stator, that generates elliptical displacement at the centers of the inner surfaces, the finite element analysis program ATILA was used. The analyzed results were compared to the experimental results. As result, the model EL10W3T0.5_CL7 which generates the maximum elliptical displacement was chosen by analyzing the resonance mode according to changes in frequency.