a rotatable rotor;

a housing configured to house the rotor;

a magnetic bearing having a first magnet arranged at a periphery of a magnet holder fixed to the housing and a second magnet arranged in the rotor to face the first magnet in a radial direction; and

an adjustment member configured to adjust a position of the first magnet relative to the second magnet,

the adjustment member having:

a main body portion having, in an inner peripheral surface thereof, a second thread shape to be fitted in a first thread shape formed at the periphery of the magnet holder and moved in a direction along a rotation axis of the rotor by rotating relative to the magnet holder to adjust the position of the first magnet relative to the second magnet, and

a protrusion protruding from an upper surface of the main body portion, and

the protrusion having, on an outer peripheral side of the main body portion, a contact target surface contactable with a first tool configured to rotate the main body portion from an upper-surface side of the main body portion and contactable with a second tool configured to rotate the main body portion from a side-surface side of the main body portion.