There is provided a wired circuit board assembly that prevents breakage of the flexing portion of a wired circuit board supported by a support frame. In a wired circuit board support sheet, a plurality of wired circuit boards include a base insulating layer, a conductor pattern, and a cover insulating layer which are formed on a support board are supported by a support frame in such a manner that they are arranged and aligned in mutually spaced relation. Each of the wired circuit boards has a flexing portion formed by removing the support board to obtain a flexing property. In addition, second connecting portions are provided in spanning relation between the flexing portion and the vertical frame parts of the support frame.