In this study, basic researches on stainless steel, copper and aluminum plates to develop a method using a thermal camera were conducted. In this study, the corrosion characteristics of all metal surfaces with time were evaluated indirectly rather than directly. The change in emissivity of the metal surface with increasing degree of corrosion was quantitatively evaluated. From these studies, the temperature showed high value due to the corrosion in the metal plate which had the same temperature, and the RGB value extracted according to the corrosion time showed a clear trend. In the case of stainless steel, the emissivity of the surface is physically changed by about 4% due to the corrosion. Therefore, it is confirmed that the degree of corrosion by the thermal image can be sufficiently evaluated. The copper plate and the aluminum plate corroded in the salt solution (concentration 10%, 20%, 30%) at room temperature were clearly distinguished from the RGB value tendency for stainless steel. However, as the concentration increased and the time became longer, the corrosion of the surface was found to be worse, and it was confirmed clearly in the thermal image.