when making contact with the sprocket s as it is sandwiched between the bushing 40 and the sprocket s for example while the roller 80 described above is curved entirely along its axial direction the roller may be curved only at both ends to reduce in diameter outward in the axial direction and not curved in the middle in this case the middle part of the roller is kept cylindrical so that the outer circumferential surface of the roller 80 makes contact with the sprocket s over a predetermined distance along the axial direction of the roller in the middle of the roller sprocket contact portion 81 which will minimize tilting of the roller 80 relative to the sprocket s while embodiments of the present invention have been described in detail the present invention is not limited to the above described embodiments and may be carried out with various design changes without departing from the scope of the present invention set forth in the claims for example while the roller chain was described as a timing chain of a car engine in the embodiments above the purpose of use of the roller chain of the present invention is not limited.