A falling sensor is provided, which detects a falling of a magnetic disk drive or an information processing device installed with said magnetic disk drive and which is effective for avoiding physical damages of magnetic heads and magnetic disk media. The magnetic disk drive or the information processing device, include an unload mechanism moving or evacuating said magnetic head from a surface of said magnetic disk media, and a falling sensor comprising a conductive flexible beams 9 or members having a compatible function, a conductive weight 10 supported by these beams and a conductive wall 11 arranged to be made contact or non-contact with said weight 10. The sensor can detect a falling of the magnetic disk drive or the information processing device which is typically a notebook personal computer installing with the magnetic disk drive, and evacuate the magnetic head by the unload mechanism. The conductive wall 11 can be formed as a tubular member.