Bearing

A bearing comprising:

• a first raceway member whose outer peripheral surface includes an annular first raceway surface;
• a second raceway member whose inner peripheral surface includes an annular second raceway surface facing the first raceway surface;
• a plurality of cylindrical rollers arranged in a circumferential direction such that the cylindrical rollers contact the first raceway surface and the second raceway surface in an annular rolling path along the first raceway surface and the second raceway surface;
• and
• a separator adjacent to the cylindrical rollers in the circumferential direction,
• the separator having a cylindrical shape,
• an outer peripheral surface of the separator having an annular groove defined by a groove wall surface, a shape of the groove wall surface in a cross section including a center axis being an arc shape,
• the separator being oriented such that the groove wall surface contacts outer peripheral surfaces of the cylindrical rollers adjacent to the separator in the circumferential direction,
• the groove wall surface having a curvature radius larger than a curvature radius of the outer peripheral surfaces of each the cylindrical roller.