PURPOSE: To prevent the leakage of gas from an exhaust passage and a motor room, respectively, and preventing corrosion and exhaust loss, and lightening the thrust force thereby miniaturizing a magnetic bearing, by arranging a two stages of auxiliary pump stages between an eddy current pump and said motor room.

CONSTITUTION: For the pump main body, an eddy current pump stage 3 and a motor 4 are accommodated inside a housing 9, and also a rotor part interlocking with the motor 4 is supported floatingly through a magnetic bearing 5. In this case, the first auxiliary pump stage 6 is arranged between the eddy current pump stage 3 and a bulkhead 95, and this inlet, with the outlet of the eddy current pump 3, and besides the outlet, with the exhaust port 9 of the casing 9, are made to communicate, respectively. On the other hand, the second auxiliary pump stage 7 is arranged between the motor room 40 and the first auxiliary pump stage 6, and this inlet, with the motor room 40, and the outlet, with the outlet of the first auxiliary pump stage 6, are made to communicate, respectively. And, a pressure area is made on the side of the outlet of the first auxiliary pump stage 6, and also exhaust is performed to this pressure area with the second auxiliary pump stage 7.