To reduce relative variation in a radial direction, of a rotary shaft between a bearing and the rotary shaft.

A bearing includes: a support portion having a first surface arranged near a peripheral surface of a rotary shaft; and a plurality of rolling portions arranged between the peripheral surface and the first surface. The support portion includes a slit having an open end formed on the first surface, and, in a directional view orthogonal to an axial direction of the rotary shaft, the open end has a shape non-parallel to the axial direction.