A complex dielectric film formed as an insulation film between oppositely facing conductors is made of an insulator and a non-insulator. The insulator and the non-insulator are formed to align in series in a serial model, to contain the non-insulator in the insulator in a serial-parallel model, and to align in parallel in a parallel mode 1. The insulator may be SiO.sub.2, Si.sub.3 N.sub.4, or other like material, and the non-insulator may be a metal, semi-metal, semiconductor containing conduction electrons, organic material containing conduction electrons, or other like material. The volume ratio of the non-insulator is chosen to an appropriate value in accordance with the designed value of the effective dielectric constant.
