PURPOSE: To provide a connecting apparatus for enclosed bus in which downsizing is realized by constituting a bus mounting/demounting apparatus only of a bellows without employing an enclosed tank while preventing gas pressure load from being applied to the outside.

CONSTITUTION: When machines installed on the opposite sides are separated, bolts 6 are removed and then a second adapter flange 4 is removed from the outer periphery of a first adapter flange 3 and a master bellows 1. The master bellows l movable along the axial direction of a mounting/demounting apparatus is moved to lap over the outer periphery of any one slave bellows 2 thus separating two slave bellows 2, 2 from each other. The master bellows 1 having inner diameter larger than the outer diameter of the first adapter flange 3 can move freely. A tool is inserted through a space formed between slave bellows 2, 2 on the opposite sides thus removing a split conductor 10 and inner conductors 9, 9 on the opposite sides.