A storage device protection system has a disk for storing data, the disk including a disk medium and a buffer for writing data to the disk medium. The device includes: a detecting unit for detecting an operation to cut off a main power supply of the device; an access suspending unit for suspending access to the hard disk when the detecting unit detects the operation; a writing unit for writing data in the buffer to the disk medium when the detecting unit detects the operation; and a power cutoff unit for cutting off the main power supply after the writing operation of the medium writing unit.