A cylindrical grooved cam with a plurality of grooved cams provided on its inner cylindrical surface comprises an inner tube having at least two guide walls that are provided on its lower edge and represent one guide wall line of the grooved cam to be formed on the inner cylindrical surface; and an outer tube having at least two guide walls that are provided on its upper edge of protruded area on its cylindrical inner surface and represent the other guide wall line of the grooved cam to be formed on the inner cylindrical surface; wherein the inner tube is to be inserted into the outer tube from above so that the guide walls of the inner tube and the counter part guide walls of the outer tube form the grooved cams on the inner cylindrical surface of the cylindrical grooved cam.