Vacuum pump

A vacuum pump comprising:

• a rotor;
• a stator;
• a casing which houses the rotor and the stator;
• an annular member to which a rotational force of the rotor is directly or indirectly applied when the rotor contacts the annular member during rotation of the rotor;
• a piping connection portion which is connected to the annular member and to which external piping is connected;
• a rotation suppression means for suppressing rotation of the annular member by the rotational force separately from a connection portion between the annular member and the casing;
• and
• a base portion disposed at a bottom portion of the casing, the base portion including a first hole, wherein:
• the rotation suppression means includes a rotation regulation portion which is formed in the annular member and a rotation regulation member which protrudes in an axial direction from the base portion and comes into contact with the rotation regulation portion by the rotational force,
• the annular member includes a flange and a second hole or a notch formed in the flange,
• the rotation regulation portion is the second hole or the notch,
• the rotation regulation member is a bolt fixed to the first hole of the base portion by screw connection along the axial direction,
• when rotor contacts the annular member, a portion of the bolt protruding from the base portion contacts with an inner surface of the second hole or the notch of the flange, and
• when the rotor does not contact the annular member, a gap is provided between the portion of the bolt protruding from the base portion and inner surface of the second hole or the notch of the flange.