A shielding apparatus for use in a printed circuit board shields electronic circuitry mounted on the printed circuit board against interfering electric waves. The shielding apparatus comprises a multi-layer printed circuit board having a circuit trace printed on a middle layer and a ground trace printed on each of the surface layers. Circuitry blocks consisting of a plurality of electrical elements are mounted on the top surface of the printed circuit board and are electrically connected to one another by the circuit trace. Metallic cases are provided on the top and bottom surfaces of the printed circuit board for covering the circuitry blocks and are in contact with the ground trace.
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