A real time file alteration sensing-based automatic backup device includes: a backup target selection unit selecting one or more backup targets that are accessible over a network and are subjected to backup; a content alteration sensing unit sensing in real time whether contents of the one or more backup targets are altered or scanning all the backup targets for sensing at particular-time intervals; a backup data generation unit generating, when the alteration of the content of the backup target is sensed, backup data containing information required for recovery of the sensed backup target; and a backup data storage unit storing the generated backup data.