A portable computing device prevents a magnetic disk unit protecting function from impairing usability for a user when the processor is used as a tablet PC. The portable computing device includes a magnetic disk unit, a magnetic disk unit protecting section operable when predicting an occurrence of an impact to carry out a magnetic disk unit protecting function for retracting a head of the magnetic disk unit, and a detecting section that detects whether a user is holding the portable computing device or not, and responsive to detecting that the user is holding the portable computing device, temporarily deactivating the magnetic disk unit protecting function.