On a surface of a film substrate made of an insulating synthetic resin, which is formed by connecting an approximately quadrangular first film substrate and an approximately quadrangular second film substrate through a bent portion, a ground electrode formed to cover at least a part of the second film substrate, and a first electrode layer formed of one of the wiring patterns on a part of the first film substrate are formed. An insulating film made of an insulating resin is formed on the first electrode layer, a second electrode layer formed of the other of the wiring patterns is formed on a surface corresponding to the part of the first film substrate of the insulating film, and the film substrate, the first electrode layer and the insulating film are bent in the bent portion such that the rear surfaces of the film substrate face each other.