A method for adjusting the warpage of a wafer, includes providing a wafer having a center portion and edge portions and providing a holding table having a holding area thereon for holding the wafer. The wafer is placed onto the holding table with the center portion higher than the edge portions and thereafter pressed onto the holding area such that the wafer is attracted to and held onto the holding table by self-suction force. The wafer is heated at a predetermined temperature and for a predetermined time in accordance with an amount of warpage of the wafer in order to achieve a substantially flat wafer or a predetermined wafer level.