To improve maintenance performance by simplifying the structure of the vicinity of an air inlet and an air outlet.

A vacuum pump 100 comprises main and sub screw rotors 120 and 150: a housing 110 having an air inlet 110a and an air outlet 110e formed in a wall part and provided at an internal part with a main rotor containing chamber 110b to contain the main screw rotor 120 and a sub rotor containing chamber 110d to contain the sub rotor 150. The vacuum pump sucks compressive fluid and compresses and discharges sucked compressive fluid. The main screw rotor 120 is rotatably supported in a cantilever state from the opposite side of the air inlet 110a and the sub screw rotor 150 is rotatably supported in a cantilever state from the opposite side of the air outlet 110e.