To make the cam-follower device be small-sized and be light in weight while securing the necessary durability by improving the durability of a supporting shaft 9 in a roller.

Hardness on the surface layer of the supporting shaft 9 is made to be ≥650 Hv and on the same position, the retained austenite ratio is made to be 15 to 40 vol%. Further, the hardness of a core part, existing nearer to the center from the above surface layer, is made to be 200 to 300 Hv.