Disclosed is a turbo-molecular pump, which comprises a rotor including a first cylindrical body formed with a part of a plurality of rotating blades arranged in multistage, a second cylindrical body integrally connected to an outer peripheral region of a downstream end of the first cylindrical body and formed with the remaining rotating blades, and a stress-releasing protrusion extending from the downstream end of the first cylindrical body along a direction of a rotation axis of the rotor. The turbo-molecular pump of the present invention can reduce a stress in the downstream end of the first cylindrical body.