Before recording data included in a data mask on a holographic medium, the data mask and the holographic medium are aligned by an aligner, which includes a beam supplying unit for supplying an incident laser beam; a transferring unit for receiving the incident laser beam and producing a focused laser beam; a reflecting unit including the holographic medium for receiving the focused laser beam through a pinhole and then reflecting the received laser beam back to the pinhole, wherein the reflected laser beam passing through the pinhole returns to the transferring unit and then is converted into a return laser beam by the transferring unit; and a detecting unit for checking the amount of the return laser beam to determine whether the pinhole and the holographic medium are aligned or not.