A device to fix a substrate for a thin film sputter, includes a mask, a mask pressing plate, a magnetic body, and a driving unit. The mask having patterns is positioned under the substrate so as to form the patterns on the substrate. The mask pressing plate is positioned over the substrate and moves toward and contacts a back surface of the substrate at a predetermined pressure. The magnetic body is placed over the mask pressing plate and moves toward the mask pressing plate so as to have the mask adhere closely to the substrate by a magnetic force of the magnetic body. The driving unit applies a driving force to move the magnetic body. Where the mask pressing plate descends, the mask pressing plate adheres closely to the substrate. Thereafter, the magnetic body descends toward the back surface of the substrate which is supported by the mask pressing plate. The mask underneath the substrate adheres closely to a front surface of the substrate by the magnetic force of the magnetic body. Accordingly, since the substrate is multi-step supported, the alignment of the mask underneath the substrate is not dislocated.