The problem of large deflection of a circular ring plate clamped along the outer and inner edges is treated here by the approximate method which was proposed before by the writer, and the maximum deflection and each edge stress are calculated for the radius ratios 0, 1/4, 1/2, and 3/4. In order to study the accuracy of approximation, the case where the flexural rigidity vanishes is considered in detail and the experiment is carried out for the radius ratios 0 and 1/4.