In the development of the advanced spent fuel management process based on the molten salt technology, it is essential to choose the optimum material for the process equipment handling molten salt. As a part of assessment of the structural material for the molten salt handling system, corrosin behavior of stainless steels of 304 and 304 L in the molten salts was investigated in the temperature range of 650~750 ℃. In a mixed molten salt of LiCl-Li2O, the oxide scale of LiMO2(M, Cr, Fe) was formed at the rate of similar parabolic kinetics. But in the mixed molten salt of LiCl-Li2O-Li3N, the nitride scale of CrN was formed at the rate of linear kinetics. The corrosion rate of the stainless steel, 304 in the mixed molten salts of LiCl-Li2O and LiCl-Li2O-Li3N was higher than that of 304 L.