An analysis is presented for the free vibration of a cantilever folded plate. For this purpose, the deflection displacements of the plate are written in a series of the products of the eigenfunctions of a cantilever beam and a cranked free–free beam parallel to the clamped edge of the plate. The kinetic and strain energies of the plate are evaluated analytically, and the frequency equations are derived by the Ritz method. The method is applied to cantilever folded plates with and without structural symmetry, and the natural frequencies and the mode shapes of vibration are calculated numerically giving the results.