PROBLEM TO BE SOLVED: To provide a Roots type vacuum pump having high versatility and capable of efficiently preventing liquefaction and solidification of gas, and a method for operating the Roots type vacuum pump.SOLUTION: A Roots type vacuum pump 1 comprises a plurality of pump chambers 40c in which Roots type rotors 51 are arranged, compresses and exhausts sucked gas in multiple stages in the plurality of pump chambers 40c, and comprises a compressed gas return device 70 for returning a portion of compressed gas exhausted from at least one pump chamber 40c out of the plurality of pump chambers 40c to the suction side of the pump chamber 40c.SELECTED DRAWING: Figure 2
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