A soundproof material may comprise, in order: a first electrically conductive ferromagnetic layer, a charged insulator layer, and a second electrically conductive ferromagnetic layer. A charged site at the charged insulator layer may be electrically insulated from the first electrically conductive ferromagnetic layer and/or the second electrically conductive ferromagnetic layer. When a sound causes vibration of any among the first electrically conductive ferromagnetic layer, the charged insulator layer, and/or the second electrically conductive ferromagnetic layer, this causes alteration of a magnetic field at the first electrically conductive ferromagnetic layer and/or the second electrically conductive ferromagnetic layer, soundproofing being carried out when acoustic energy of the sound wave is lost as thermal energy.