An adhesive agent layer for bonding a support plate (1) and a wafer (5) is in a three-layer configuration in which a hard layer (31) is sandwiched between soft layers (32) and (33) from above and below. Both the top and bottom surfaces of the adhesive agent layer are soft adhesive agent layers, which results in an excellent bonding affinity with the wafer 5 and the support plate (1). Accordingly, the peripheral portion of the wafer (5) can be prevented from being lifted before a dicing process. Further, because the sandwiched adhesive agent layer is the hard adhesive agent layer (31), even when the non-adhesive surface of the support plate (1) is vacuum suctioned, or when a pressure is applied from a grinder, the hard adhesive agent layer (31) is not deformed according to the soft adhesive agent layer (33) being drawn or pushed into through holes (2).