SUS 304 stainless steel plate was dipped in molten Al-Si alloy laving different Si concentrations, i.e., hypoeutectic, eutectic, and hypereutectic. The effect of Si concentration on coating layer formation was studied by metallographic observation and EPMA analysis. Diffusion heat treatment of hot-dipped samples was also conducted and the change in the coating layer structure examined. Metallographic examination showed that the adhered layers of samples hot-dipped in hypoeutectic and eutectic Al-Si alloy baths are the same as the solidified structures of conventionally cast Al-Si Alloys. The CrSi₂-Al_x phase was observed in the adhered coating layer of the sample hot-dipped in hypereutectic alloy. The amount of CrAl₂-Al_x increased with increasing bath temperature and immersion time. Fe-Al-Cr-Si alloy layers formed at the interface of the stainless steel and molten alloy, and grew to a maximum thickness of about 20μm. The alloy layer growth rate and maximum thickness did not depend on Si concentration in the Al-Si alloy bath.