The invention provides a turbo-molecular pump (18), which can restrain attachment of depositions onto component parts thereof and is used for discharging deposition-causing gas from a chamber (11), including: a rotor (37) of a rotating shaft (36) along the exhaust stream; a casing (38) holding the rotor (37); multiple rotating wings (39) protruding from the rotor (37) relatively to the rotating shaft (36) vertically; and multiple static wings (40) protruding from the casing (38) relatively to the rotating shaft (36) vertically. Multiple rotating wings (39) are divided into multiple rotating wing groups (41); multiple static wings (40) are divided into multiple static wing groups (42); each rotating wing group (41) and each static wing group (42) are collocated mutually along the rotating shaft (36), supplying the gas at more upstream opening of exhaust stream relative to the rotating wing group (41) at lowest downstream side to deposition-suppressing gas with Ar molecule.