In order to avoid destruction of recorded data on the magnetic disk due to a shock when portable equipment incorporating a magnetic disk falls from a person's hand or similar, or to minimize damage to the magnetic head and magnetic disk device, in the portable equipment incorporating a magnetic disk device, the magnetic disk device 1 is provided with a magnetic head retraction mechanism and with a held-in-hand detection mechanism which detects whether the equipment is held in a person's hand. When the held-in-hand detection mechanism detects that the equipment is not held in a person's hand, the retraction mechanism causes the magnetic head 5 to be retracted from the recorded data portion of the magnetic disk 3 to the outside, so as to protect the magnetic disk device 1 and the data recorded on the magnetic disk from shocks.