NOVELTY - The abrupt metal-insulator transition (MIT) device has abrupt MIT structures (600,600a) formed on an upper surface and a lower surface of a substrate (100) respectively. Each abrupt MIT structure has a characteristic of an insulator below a predetermined limit voltage and has a characteristic of a metal at or over the limit voltage, and comprises electrode thin films contacting abrupt MIT thin films (450,450a, 460,460a).    USE - Used for e.g. 800KV-SF6 gas insulating switch gear (GIS) used in a substation.    ADVANTAGE - A high-voltage noise circuit suitable for each electric/electronic system can be designed by suitably adjusting the structure and material of the abrupt MIT device and adequately connecting abrupt MIT devices to one another. The high-voltage noise can be removed effectively, by using serially-connected abrupt MIT devices.    DETAILED DESCRIPTION - The abrupt metal-insulator transition thin film is formed of material selected from the group consisting of an inorganic semiconductor to which low-concentration holes are added, an inorganic insulator to which low-concentration holes are added, an organic semiconductor to which low-concentration holes are added, an organic insulator to which low-concentration holes are added, a semiconductor to which low-concentration holes are added, an oxide semiconductor to which low-concentration holes are added, and an oxide insulator to which low-concentration holes are added. The materials include oxygen, carbon, semiconductor element of III-V and II-IV groups, transition metal element, a rare-earth element, and a lanthanum-based element. INDEPENDENT CLAIMS are also included for:    (1) high-voltage noise removing circuit; and    (2) electric and/or electronic system comprising the circuit.    DESCRIPTION OF DRAWING(S) - The figure shows the cross-section of the double-sided planar-type abrupt MIT device.    Substrate (100)    Buffer layers (200a,200b)    Electrode thin-films (450,450a,460,460a)    Abrupt MIT structures (600,600a)