The invention relates to an apparatus for fastening a data storage device, which is used to fasten a data storage device or module with a plurality of fixing holes. The apparatus for fastening a data storage device of the invention includes a housing, a driving plate, at least one lateral fastening plate, and an elastic member. As the driving plate moves, the lateral fastening plate is pushed to move laterally, whereby the locating pins move into or out of the locating holes on the sidewalls of housing to remove or fasten the data storage device. The data storage device can be fastened to a housing of a computer without screws, and a user can operate more conveniently.