Provided is a Method and Computer Apparatus being capable of safely and reliably making a backup copy of data stored on the Hard Disk Drive (HDD). A user places a PC in a hibernation state by inputting a particular key operation under a typical OS environment. The working state data is stored on the HDD just before the backup copy of data is created. During the process of backup, an OS in a hidden partition of the HDD is booted so as to execute a program for making a dead copy of the HDD. When the dead copy processing by the copy program from the HDD to the backup HDD is completed, the PC system's operation is resumed and an OS is booted so as to recover from the hibernation state to the original state.