To provide a vacuum pump having a simple structure with high efficiency, which can extract an exhaust gas directly from a vacuum chamber under a high degree of vacuum to the atmosphere.

A pump chamber 7 of which both sides are shut tightly with a first terminal wall 5 and a second terminal wall 6, and the chamber is divided into a first pump chamber 9 and a second pump chamber 10 with a dividing wall 8. An intake vent is provided on the first terminal wall 5, and an extraction port 13 is provided on the second terminal wall 6. Further, a connecting hole 15, which connects the first pump chamber 5 with the second pump chamber 6, is provided on the dividing wall 8. One pair of pawl rotors 26, 27 are put in the first pump chamber 9, thereby a pawl pump 2 is constituted. Further, one pair of screw rotors 28, 29 are put in the second pump chamber 10, thereby a screw pump 3 is constituted. So that, a gas being extracted from the vacuum chamber is first compressed by the pawl pump 2, next compressed by the screw pump 3, then purged into the atmosphere.