Abstract: The present invention discloses a portable data storage device, and more particularly, to a portable data storage device with a very small-sized hard disk, which improves the transportability and user convenience of a data storage device and increase use efficiency by storing data of an information system and allowing a data access if required. The portable data storage device can store a large capacity data by connecting to an information system via a media connector supporting an interface and then storing data of the corresponding information system on a very small-sized hard disk, thereby obtaining transportability. In addition, the portable data storage device provides user convenience by allowing a user to access to the data stored in the data storage device.