Provided is a vacuum pump in which the flexing of a rotating cylinder made of a fiber-reinforced resin can be reduced as much as possible to sufficiently reduce the gap between the rotating cylinder and a fixed cylinder, and exhaust performance can thereby be improved to great effect. A vacuum pump comprising a thread groove pump portion equipped with a fixed cylinder portion (2) having a spiraling thread groove portion (1) provided in an internal peripheral surface, and a rotating cylinder portion (3) placed inside the fixed cylinder portion (2), the thread groove pump portion exhausting through a spiraling exhaust flow channel due to the rotating cylinder portion (3) being caused to rotate, and the exhaust flow channel being formed from the thread groove portion (1) and an external peripheral surface of the rotating cylinder portion (3). The rotating cylinder portion (3) is configured by stacking a plurality of fiber-reinforced resin layers, and the outermost fiber-reinforced resin layer is thicker than the adjacent layer.