To provide a capacitative device capable of accurately securing a capacitance value, a variable capacitative device capable of sufficiently securing a capacity variability rate, and a resonance circuit that uses the capacitative devices. A capacitative device according to the present invention includes a capacitative device body constituted of a dielectric layer and at least a pair of capacitative device electrodes that sandwich the dielectric layer and cause a desired electric field in the dielectric layer; and stress adjustment portions to adjust a stress caused in the dielectric layer of the capacitative device body.