A monolayer or a multilayer of niobic acid nanosheets is attached to form a dielectric film, and other electrode is arranged on the surface of the dielectric film to construct a dielectric element, and the dielectric element thus provided realizes both high permittivity and good insulating properties even in a nano-region. Also provided is a method of producing the element at low temperatures with no influence of substrate interface deterioration and composition deviation thereof. The method entirely solves the problems of substrate interface deterioration and the accompanying composition deviation and electric incompatibility, and solves the intrinsic problem of “size effect” that the film thickness reduction to a nano-level lowers the specific permittivity and increases the leak current, and the method takes advantage of the peculiar properties and good ability of texture and structure regulation that the niobic acid nanosheet has.