Storage device comprising a driving method and a nanogap switching element of the nanogap switching element

A nanogap switching element is equipped with an inter-electrode gap portion including a gap of a nanometer order between a first electrode and a second electrode. A switching phenomenon is caused in the inter-electrode gap portion by applying a voltage between the first and second electrodes. The nanogap switching element is shifted from its low resistance state to its high resistance state by receiving a voltage pulse application of a first voltage value, and shifted from its high resistance state to its low resistance state by receiving a voltage pulse application of a second voltage value lower than the first voltage value. When the nanogap switching element is shifted from the high resistance state to the low resistance state, a voltage pulse of an intermediate voltage value between the first and second voltage values is applied thereto before the voltage pulse application of the second voltage value thereto.