Corrosion resistance of various surface treated steel sheets through A.C. impedance technique was examined and also compared with that obtained from salt spray test. A.C. impedance spectra was measured from 10 m ㎐ to 10000 ㎐ with applied amplitude of ± 10 mV at the open circuit potentual in 0.2% NaCl solution. Several equivalent circuits for surface treated steel sheets could be suggested from A.C. impedance spectra and the value of Rp(polarisation resistance) in equivalent circuits was used to evaluate corrosion resistance in this study. Thus, it could be determined that A.C. impedance technique is the simple and exact evaluation method for surface treated steel sheet in comparison with results of salt spray test.