Formerly, one of us (T.A.) studied the elastostatic properties of the corrugated diaphragm, assuming it as an orthotropic elastic plate by smearing out the effect of the corrugations over a wave length, and found that the calculated results agreed well with those of the experiments. In this paper, analyzing the vibration properties of the corrugated diaphragm under the same assumptions as the static case, we obtained the approximate formulas for the natural frequencies of symmetric and asymmetric modes including the effect of concentrated mass. Furthermore, by the energy method, we studied the effects of initial tension and concentrated mass on the natural frequencies. In order to check this analysis, some experiments were performed. The experimental results showed good coincidence with the correspondig formulas, when the anisotropy parameter α is not so large.