In one embodiment, a disk drive has a solenoid and spring for turning a ramp mechanism about a rotating shaft. When the drive operates, since the ramp mechanism moves out from the magnetic disk by the force of the solenoid, the outer peripheral edge of a magnetic head that has formerly been unusable can be used as a data read/write region, without the magnetic head interfering with the fins of the ramp mechanism. During a non-operating state of the drive and in case of a power interruption, the force of the spring returns the ramp mechanism to a position at which the magnetic head can be unloaded. This construction allows the storage capacity of the drive to be easily increased without sacrificing the shock resistance of the ramp mechanism.