Abstract: Gas circuit breakers, gas insulated disconnecting switches, current transformers, gas insulated feeding bus bars and other main component devices making up a gas insulated power switch-gear apparatus used for the power electric substation or the power electric switching station are arranged in at least one straight line in a horizontal plane. Gas insulated main bus bars are arranged substantially at right angles to the straight lines including the component devices, in a different plane parallel to the above-mentioned plane containing the devices, thus reducing the height of the apparatus as a whole and at the same time improving the earthquake-proofness thereof.