A vacuum pump has a working space, a bearing space, a dividing wall arranged between the working space and the bearing space and at least one rotor shaft which extends through the dividing wall and which forms a gap with the dividing wall and having a blocking device for blocking between the working space and the bearing space. The blocking device is formed by a Siegbahn pump stage which is configured for providing a pump action passing through the gap between the working space and the bearing space.