After interruption of blood supply to central nervous system tissue, cerebral edema sets in. The transmission axis of the first polarizing layer and the transmission axis of the second polarizing layer orthogonally intersect with each other. The ridge formed as a result exerts pressure onto the elastic sealing material disposed around the electrode in a tubular shape, thereby producing a hermetic seal between the electrode surface and the sealing material, and between the sealing material and the wall of the housing opening. Then, a flexible film is adhered onto the etched surface of the substrate, and thereafter the protection film is peeled to produce a flexible electronic device.