A printed wiring board is made of first and second substrates superimposed on each other. The first and second substrates respectively include a core layer made of resin containing carbon fibers. The second substrate has the outline different from that of the first substrate. A stepped surface is defined on the front surface at least of the first substrate. Electrodes can be formed on the stepped surface as well as on the back surface of the first substrate and the front surface of the second substrate. This structure enables detection of an electric signal from the stepped surface. A further flexibility can thus be achieved in locating electrodes as compared with a conventional printed wiring board having uniform substrates simply superimposed on each other. This results in an expanded use or purpose for a printed wiring board.