In order to compensate for out-of-straightness of shafts, an automatic straightening process composed of an automatic measuring module, an automatic control unit and operating softwares was developed with a hydraulic press. The out-of-sraightness of each shaft was measured automatically in the measuring stage. An optimal pressure point was determined to minimize TIR value of the shaft according to press count of 3-points bending process. In the geometric adaptive control procedure, punch stroke and springback of the shaft were predicted by an observer using on-line measured values of press force and deflection amount I each press count. An automatic straightening machine was realized with the measuring module, the GAC module, PLD, IBM-PC and the operating software on the hydraulic press. the validity of the proposed straightening process was confirmed through a series of experiments with cam shafts.