A falling sensor is provided, which detects a falling of a magnetic disk drive or an information processing device installed with the magnetic disk drive and which is effective for avoiding physical damage of magnetic heads and magnetic disk media. The magnetic disk drive or the information processing device, include an unload mechanism moving or evacuating the magnetic head from a surface of the magnetic disk media, and a falling sensor comprising a conductive flexible beam or member having a compatible function, a conductive weight supported by these beams and a conductive wall arranged to be made in contact or non-contact with the weight. The sensor can detect a falling of the magnetic disk drive or the information processing device, which is typically a notebook personal computer installed with the magnetic disk drive, and evacuate the magnetic head by the unload mechanism.