A vacuum interrupter includes: one movable contact fixed on a movable contact stem; and one fixed contact with a fixed contact stem. The fixed contact and the movable contact are located in a electrically insulating tube, which is vacuumtightly closed by metal lids at boths sides. The fixed contact stem is placed vacuumtightly on one of the metal lids, and the movable contact stem is guided trough an opening of the opposite metal lid via an axially extendable vacuumtight bellow. In order to create a twist protection of the movable contact stem, a ring disc shaped plastic part with a central opening, through which the movable contact stem is guided, is connected externally to the vacuum interrupter such that inner spanner flats inside the opening complementarily fit closely to external spanner flats of the movable contact stem.