An energy harvesting device includes: a first nanoporous electrode and a second nanoporous electrode, each of which is configured to which store electrical charge; a first current collector connected to the first nanoporous electrode and a second current collector connected to the second nanoporous electrode; and an enclosure that contains the first and second nanoporous electrodes and the first and second current collectors and transfers a force applied from the outside to the first nanoporous electrode and the second nanoporous electrode, wherein at least one of the first nanoporous electrode and the second nanoporous electrode comprises an ion conductive polymer.