The present invention is provided to satisfy insulation and conductivity performance requirements, to reduce the size of a gas insulated bus, and also to make conditioning for a particle more reliable. In a gas insulated bus having a conductor supported in a cylindrical metal container via an insulator, insulating gas being contained in the metal container, the metal container has an expanded diameter part formed over a given range in an area of the metal container in which the insulator is positioned and a reduced diameter part formed over the entire area of the metal container except for the expanded diameter part. Thus, when the temperature of the insulator increases during conduction, heat from the insulator is transferred to the metal container via a large space in the expanded diameter part and released to the air through a large outer surface of the expanded diameter part of the metal container.