A wired circuit board has an insulating layer extending in a longitudinal direction, a conductive layer having a plurality of signal wirings covered with the insulating layer and arranged in mutually spaced-apart and parallel relation in a perpendicular direction to the longitudinal direction and a thickness direction of the insulating layer, and connecting terminals provided on both longitudinal ends of each of the signal wirings and exposed from the insulating layer, and a ground layer covered with the insulating layer and formed to surround each of the signal wirings in a perpendicular direction to the longitudinal direction. A slit along the longitudinal direction is formed between each of the signal wirings in the insulating layer.