To evaluate the performance of Zr65Al7.5Ni10Cu17.5 amorphous alloy for the biomedical use, the effects of chloride ion, Cl−, pH, and dissolved oxygen, DO, on the anodic polarization behavior of the alloy were examined in phosphate buffered solutions. Polarization resistance, Rp, at open-circuit potential, Eopen, and pitting potential, Epit, were determined from the polarization curve. Compositions of passive film generated in a pH-7.5 solution with various concentrations of DO were characterized with X-ray photoelectron spectroscopy. In the solution with pH 7.5, the Epit decreased with the increase in logarithm of Cl− concentration, [Cl−], and showed the highest value with the same DO concentration, [DO], as that in vivo. The concentrations of hydroxide group, [OH−], and phosphate ions, [HxPO4(3−x)−], in the passive film were changed with various [DO]s, and the Epit decreased with the increase in [OH−] and [HxPO4(3−x)−]. In the solution with pH 2.2, the Epit was higher than the Eopen with and without DO. Therefore, this alloy may be resistant to the pitting corrosion in vivo.