A data protection device capable of securing data in a data storage device is disclosed, comprising a disk space allotment unit, a marking unit, and an archiving unit. The disk space allotment unit undertakes to reorganize multiple sectors in the data storage device for allotment of disk space to newly defined sections to be used in the present scheme, such as a working data section, a sector index table and a duplicate data section. The marking unit is to check and update the data flags in the sector index table when data are written into respective sectors of the working data section, where the data flag indicates whether the write status of certain sector is enabled. The archiving unit is to reverse the above process so as to restore the original data in the working data section and data flag in the sector index table.