A method of producing a built shaft in which at least one part, particularly a cam, is mounted on the shaft, particularly a camshaft, includes inserting the shaft into an opening of the part. Before mounting the part, the shaft is stretched by a stretching and tightening device such that an original diameter in the area of at least one fastening location is reduced to a stretched diameter. The part is slid onto the shaft and up to the fastening location. The stretching and tightening device is then loosened to enable the diameter of the shaft to enlarge once more towards its original diameter. The part is firmly fastened at the fastening location by an interference fit in both an axial and rotationally fixed manner.