A casing that has an electronic component housed therein has a conductive layer made of a mixture of carbon fibers and a thermoplastic resin and an insulating layer where only the thermoplastic resin is exposed on a surface of the conductive layer. The casing prevents leakage of unwanted electromagnetic waves from inside, is not affected by external electromagnetic waves, has small thickness, light weight, high strength and high rigidity, and has excellent contactability with a coating.