In a switching network having cross-points constituted by semiconductor switch elements of four-layer structure of PNPN, communication channels are connected in an unbalanced configuration, and all vertical or column buses and horizontal or row buses constituting the switching matrix are individually grounded through respective capacitors, whereby the semiconductor switch elements are inhibited from erroneous firings due to application of voltages having a high raise-up rate such as high frequency noises, thereby to protect the switching network from erroneous switching operations without increasing cross-talk.
