To inexpensively provide a finished surface of high accuracy and realize the low cost while improving the bearing characteristic of a bearing device.
When a finishing tool 41 is inserted into a bearing hole 13A3, a insertion guide part 41c mounted on a tip side of the finishing tool 41 is inserted into the bearing hole 13A3 first, whereby the insertion is executed in a state that an angle and a parallel degree of an axis of a pressure contact working part 41b at a rear side continuing from the insertion guide part 41c are gradually agreed with a central axis of the bearing hole through a floating holder mechanism 42, the working by the pressure contact working part 41b is started in a state that the central axis of the pressure contact working part 41b is automatically agreed with a central axis of a bearing hole with high accuracy, and then a bearing inner peripheral surface is finished with high accuracy without remaining a sawing mark and a waving mark found in the cutting work, by the pressure plastic deformation action of the pressure contact working part 41b.