To provide a method of machining a bushing constituting a roller chain, without enlarging the inner diameter of both end parts of the bushing, so as to prevent the bushing from creasing at its inner peripheral surface and from being formed into a drum-like shape, in order to obtain a high degree of straightness of the roller chain and to prevent the roller chain from being elongated.

A columnar body obtained by cutting a wire having a predetermined diameter and used as a material is set in dies so as press punches against upper and lower end surfaces of the columnar body in order to form recesses, and then the bottom 4 defined between the recesses is punched out by the front end of a punch. Further, a tapered part 8 formed on the front end part of the punch is pushed into the bore of the columnar body in order to form a tapered surface on one end part of the inner peripheral surface, and another punch 10 having a spherical part 11 at the front end thereof and formed with a tapered part 8 is also pushed into the recess so as to form a tapered surface on the other end part.