Disclosed is a method for separating a first member (1) and a second member (2) joined to each other comprising the steps of placing a clamp ring (14) on the surface of the first member, plunging a rotating probe (17) having a screw thread on a peripheral surface thereof into the surface of the first member through a through hole (10) of the clamp ring until a tip end of the probe reaches beyond an interface between the first member and the second member, the screw thread being directed so as to lift material of the bonded part away from the second member as a lifted part. The two members can be rejoined to each other by collapsing the lifted part into a bonded part once again by using a rotating probe and a clamp ring.