Abstract: An electrolyte such as a saturated picric acid solution in a cell for measuring electrochemical polarization is placed in contact with an alloy steel such as a CrMoV steel which has been subjected to a high-temperature and stress-applied condition, and a potential is swept between the CrMoV steel and a salt bridge in the cell, whereby the Mo-rich carbide M.sub.6 C undergoes a dissolution reaction at a potential near a specified value and this reaction is visible as the secondary anode peak current, or the second appearance of peak current on the waveform of electric polarization. Since the secondary anode peak current is closely related to the amount of M.sub.6 C precipitation, the progress of degradation in the CrMoV steel can be evaluated by a simple method with good precision.