A superfinishing method for a bearing roller involves installation of a pair of parallel feed drums. The feed drums have guide thread surfaces each continuing in a spiral shape on an outer periphery, and each being driven to rotate about respective center axes. The feed drums through-feed a workpiece to be formed into a bearing roller while supporting and rotating the workpiece with the guide thread surfaces opposed to each other. The superfinishing method includes using a grinder to process an outer peripheral surface of the workpiece passing between the feed drums, varying a thread bottom angle of the guide thread surface based on positions along the feed drums in an axial direction, and superfinishing straight and logarithmic portions at both ends of the straight portion of a rolling surface of the bearing roller by one through-feed of the workpiece passing between the feed drums.