To provide a cam shaft easily fixing a cam piece on a drive shaft.

Two pairs of combinations of stepped parts 21, 24 cut off radially inward and taper parts 22, 25 connecting to the stepped parts and having different outer diameters are provided in parallel in an axial direction on an outer circumference surface of the drive shaft 2 of the cam shaft 1. Inner holes 31a, 31b of the cam pieces 3A, 3B have different inner diameters and are inclined in axial direction to engage with the taper parts 22, 25. The drive shaft 2 is inserted in the inner holes 31a, 31b in an order from the cam piece 3A under a condition where diameters of the inner holes 31a, 31b are expanded by heating the cam pieces 3A, 3B. The cam pieces 3A, 3B abut on the stepped parts 21, 24 with one end surfaces respectively, and the inner holes 31a, 31b engage with the taper parts 22, 25. Consequently, the cam pieces 3A, 3B are firmly fixed in both directions with being arranged on an axial line of the drive shaft 2.