The molten carbonate fuel cell has conspicuous feature and high potential in being used as an energy converter of various fuel to electricity and heat. However, the molten carbonate fuel cell which use strongly corrosive molten carbonate at $650^{circ}C$ have many problem. Systematic investigation on corrosion behavior of stainless steels has been done 62 mole% $Li_2CO_3$ and 38 mole% $K_2CO_3$ melt at 923 K by using steady-state polarization method and electrochemical impedance spectroscopy method. It was found that SUS 310L and Al coating specimen may be the best choice among the alloys tested in this study for molten carbonate fuel cell component material.