A wired circuit board has a metal supporting board, an insulating base layer formed on the metal supporting board, a conductive pattern formed on the insulating base layer and including at least one pair of wires arranged in mutually spaced-apart and opposed relation having different potentials, a semiconductive layer formed on the insulating base layer to cover the conductive pattern and electrically connected to the metal supporting board on one side outside a region where the pair of wires are opposed, and an insulating cover layer formed on the semiconductive layer.