Because of its stable passivation, titanium has been used in medical and dental areas. In dentistry, there are several occasions involved in the vibration, including ultrasonically vibrated tooth-brushing. There is no reports dealing with the passive film stability under such vibration conditions. It was a purpose of this study to investigate the stability of titanium passivation under vibration condition. Commercially pure titanium (Grade II) was mechanically wet-polished with #600 grit SiC paper, serving a control to this study (C). CpTi was also pre-oxidized by air-oxidation at 600oC for 10 min (O). These samples were then conditioned at –500mV (vs SCE) for 30 min, followed by polarizing from –500mV to 1500mV at scanning rate of 0.5 mV/sec in at room temperature artificial saliva solution. The vibration tests were performed by setting up the corrosion cell inside the ultrasonic cleaning chamber. It was found that C sample showed a typical polarization with IPASS of 5.5mA/cm2 and the stable passivation was maintained up to 1000mV under no vibration, but when the cell was vibrated, after showing a clear anodic dissolution, there was no stable passivation and ICORR of 0.1mA/cm2 was recorded at 1500mV. Moreover, when pre-oxidized CpTi (sample O) was polarized under no-vibration, IPASS was observed at 0.2mA/cm2 and entered a transpassivation at 1000mV. However, if the sample O was vibrated during the polarization, there was no clear passivation onset and the entire anodic portion was unstable. It was concluded that mechanical vibration disturbed stability of passivation for commercially pure titanium.