To provide a thin-film capacitor, together with its manufacturing method which comprises a dielectric thin-film of a tungsten bronze type having superior crystallinity, while using a single-crystal substrate of SrTiO3, etc., of superior general-purpose properties as a base material substrate.

Between an oxide single-crystal substrate, which is to function as a base material substrate 2 and a tungsten bronze type dielectric thin-film 4, a conductive oxide thin-film of tungsten bronze type acting as a buffer layer is inserted, so that the tungsten bronze type dielectric thin-film 4 of superior crystallinity is formed, while an SrTiO3 single-crystal substrate 3 is used as the base material substrate 2.