PURPOSE: To reduce friction resistance by double mounting two cam follower rollers(CFR) on a single shaft, applying tapered shape to a total unit of the CFR for corresponding to wall surfaces of a cam groove, and forming a part where CFR is not in contact with, in opposed surfaces of the wall surface.

CONSTITUTION: Two cam follower rollers CFR1, CFR2 are double mounted on a single shaft A with tapered shape formed as a whole. Wall surfaces W1, W2 of a cam groove, to which tapered surfaces of the CFR1 and CFR2 are respectively opposed, are formed. Cut parts, where the CFR1 and CFR2 are not brought into contact, are formed in opposed surfaces of the wall surfaces W1, W2 of the cam groove. In this way, generation of backlash is suppressed by reducing friction resistance with the CFR brought into rotation contact with the cam groove and preventing wearing.