PURPOSE: To obtain the compact turbomolecular pump by constituting the turbomolecular pump and a capacity type vacuum pump into integral form by arranging the capacity type vacuum pump in dry type as rough pump onto the exhaust side of the turbomolecular pumping part.

CONSTITUTION: The motor casing 8 for a rotary shaft 11 projects upwardly, and the movable vane 2 of a turbomolecular pump part A is installed at the upper edge. A screw pump consisting of the first screw rotor 12 and the second screw rotor 13 which revolves in interlocking with the first screw rotor 12 is arranged in an intermediate casing 6. Therefore, a rough pumping part B and a turbomolecular pump part A can be integrally made compact.