A data storage device includes a tray, a circuit board module and two storage units. The tray has a carrying space. The circuit board module includes a circuit board, a pair of adapter slots and a connection slot. The pair of adapter slots are disposed with an interval at one side of the tray, and the storage units are arranged side by side in the carrying space. Each storage unit includes a carrying box and a storage component. The carrying box is pivoted with a handle, and two sides of the handle are pivoted at opposite sides of the carrying box so that the handle is capable of rotating above the carrying box. The storage component is inserted in the adapter slot to electrically connect with the circuit board.