In this study, the equations of motion of the thin annular plate with uniform thickness were derived from the classical theory of the plate. In addition the distribution of the inplane stress and the natural frequency due to the change of the ratio of the outer radius to the inner radius was presented by the analytic method using the numerical analysis. Results were compared with those from the experiment. As a result, the strain of rotating circular plate increased as the radius and rpm became greater, and the strain of radial direction was two times greater than that of transverse direction. Besides, it was confirmed that the natural frequency increased according to the decrease of the radius keeping the thickness constant.