An oxidation behavior of 304 and 316 stainless steels were studied in dry air. After solution treatment, specimens were polished up to $1{mu}m$ $A1_2O_3$ grade and then subjected to oxidation treatment in dry air at $800^{circ}C{sim}1200^{circ}C$. The oxidation behavior between matrix and oxide scale was analyzed with SEM, EDS and XRD. When oxidation treatment was conducted at $1200^{circ}C$, large thickness of Fe oxide scale was formed on top of surface and fine $(Cr,Fe)_2O_3$ oxide film was formed below it. Cr rich zone existed at interface between metal and $(Cr,Fe)_2O_3$ oxide layer, and it was believed that this zone acted as obstacle to oxidation. Most of Ni was detected at the interface between metal and $(Cr,Fe)_2O_3$ and also detected at the interface between $Fe_2O_3$ and $(Cr,Fe)_2O_3$.