The present invention is a temporary adhesion method for temporarily bonding a support and a wafer via a temporary adhesive material, including attaching the wafer to the support via the temporary adhesive material including a complex temporary adhesive material layer that consists of a thermoplastic resin layer (A) exhibiting a storage modulus E′ of 1 to 500 MPa and a tensile rupture strength of 5 to 50 MPa at 25° C. and a thermosetting polymer layer (B) exhibiting a storage modulus E′ of 1 to 1000 MPa and a tensile rupture strength of 1 to 50 MPa at 25° C. after curing, wherein the attaching is performed by forming the layer (A) on the front surface of the wafer from a liquid composition (A′), forming the layer (B) on the support by laminating a film resin (B′), and then heating the wafer and the support under reduced pressure, or forming the layer (A) on the front surface of the wafer from the liquid composition (A′), forming the layer (B) on the layer (A) by laminating the film resin (B′), and then heating the wafer and the support under reduced pressure, and heat curing the layer (B). This temporary adhesion method facilitates temporary adhesion and separation and can increase productivity of thin wafers.