To improve the sliding rotations of pins within pin (roller) retaining holes 113a. A method of fabricating a pin (roller) retaining ring in an internal meshing gear mechanism, the mechanism having an internal gear 20 and external gears 5a, 5b put into internal mesh with the internal gear, the internal gear consisting of a pin (roller) retaining ring 110 having half-round pin (roller) retaining holes in its inner periphery and pins (rollers) 11 rotatably fitted to the respective pin retaining holes, is provided. Here, before the bore diameter &phgr;DA of a pin retaining ring base material 151 is machined to a finished diameter, the pin retaining holes 113a are cut as full round holes into the ring base material. The inner surfaces of the pin retaining holes 113a are finished by roller burnishing, and then the bore diameter of the pin retaining ring is expanded to the finished diameter to obtain the pin retaining ring having the half-round pin retaining holes. This realizes the lubrication between the pin retaining holes and the pins in a state close to fluid lubrication.