In the present invention, the performing the processing by forming a plurality of different slopes in the inner peripheral surface of each unit on either side of the axial direction of the bearing alloy of the plain bearings to easily, plain bearings working method and working apparatus is provided with plain bearings. In the processing method and apparatus, the processing holder 18 having a groove 20 and the side portions on the lateral groove formed in a stepped shape extending in the peripheral direction in the inner circumferential surface is provided, the half-bearing (half bearing) ( 11) it is pressed into both ends of the peripheral direction of the half bearing 11 by the use of and received in the process holder 18, a pressing means (24). Then, the half-bearings are to be fitted in the groove and the plastic deformation both sides of the axial direction of the half-bearing is deformed in line form on contact with the edge shape of stairs (22, 23) polygon. In this state, the shaft at both ends of the direction of the half bearing 11 is cut along a cylindrical surface with a brooch (19). As a result, the slope of the second surface having a different angle is continuously formed on both side portions in the axial direction of the bearing alloy (13) of the half bearing.