This paper addresses the fundamental understanding of sensitization phenomenon in stainless steel and a method of desensitization utilizing a high energy density beam of LASER. Degree of sensitization was evaluated with the state of the art technique of EPR and was correlated with microstructural changes characterized by TEM(STEM), SAD and SEM. Laser desensitization could be obtained with a proper choice of beam power and scanning rate under a constant beam size. As long as the scan rate was lower than a critical rate under a constant beam power, carbides and Cr depleted zone were completely disappeared. Further, as a cooling rate after laser treatment was significantly greater than a critical cooling rate for reprecipitation of carbides, re-sensitization would not be occurred during cooling. The critical scan rate increased with an increase in a beam power, but was constant regardless of the original degree of sensitization.