The oxidation behavior of the Zr-based bulk amorphous alloy (BMG;Zr-30Cu-10Al-5Ni in at.%) was studied in dry air over the temperature range 300-500℃. The kinetics results indicated that the amorphous alloy oxidized linearly at 300℃, while the parabolic oxidation was observed at 350~425℃, and the oxidation behavior at 500℃ was irregular and complicated. In general, the scales formed on the surface of the amorphous alloy were temperature-dependent, consisting of tetragonal-ZrO2 at 300℃, and of mostly tetragonal-ZrO2 as well as minor amounts of monoclinic-ZrO2 and CuO at T≥350℃.