An electret includes a substrate, and an electret layer formed on a surface of the substrate. The electret layer is an inorganic dielectric layer that has been electrically charged. The inorganic dielectric layer includes an outer layer and an inner layer that are stacked in a thickness direction of the substrate. The outer layer contains a first inorganic dielectric material as a main component which is a composite metal compound including different metal elements and has a bandgap energy of 3 eV or more. At least one of the different metal elements being a trivalent metal element. The inner layer contains a second inorganic dielectric material as a main component which is different from the first inorganic dielectric material.