A thrust bearing for use in a rolling mill, having a pair of each of working rolls and stay rolls as well as a mechanism for crossing the rolls, is provided with retainers in which pockets for retaining rolling bodies are arranged in a plurality of rows. Each rolling body, when accommodated in the pocket, has the rotating axis passing substantially the center of swing motions, which makes the bearing appropriate to the swing motions of the rolling mill. Also, centering mechanisms, collar members and stoppers are provided for the retainers, so that malfunctions can be effectively prevented.