To provide a mobile disk drive which can quickly recover from servo errors.

This drive has a second vibration proofing mechanism 40 which can change a resonance frequency of a floating section 20 by changing the length of the second coil spring 44 between a free length and a predetermined length larger than it the free length. It changes the resonance frequency to another frequency by using the second vibration proofing mechanism 40 based on the developed servo errors. Since the low tolerable acceleration of the frequency band becomes higher than before when the resonance frequency is changed, there is the strong possibility that vibration applied from the outside, even if it is equal to the previous vibration, becomes lower than the tolerable acceleration over all frequency band. Thus, it becomes possible to quickly recover from the servo errors.