To comparatively quickly and easily assemble a stopper member 8 for stopping a release lever 7 and a return spring 9 to the cam shaft 2 to a cam shaft body 2.

In this cam shaft 1, the release lever 7 and the return spring 9 as decomposing members are operatively assembled to a resin-made cam shaft body 2 formed by integrally forming a gear part 5 on a shaft part 3 having a cam part 4. The stopper member 8 for preventing the release lever 7 and the return spring 9 from dropping out of the cam shaft body 2 is mounted on the cam shaft body 2 by using a snap fit structure.