A separating apparatus for separating a composite substrate into a first substrate and a second substrate previously bonded to each other. The separating apparatus includes a support base having a supporting surface for supporting the composite substrate, a pair of side surface supporting rollers for supporting the peripheral side surface of the composite substrate placed on the supporting surface, and a separating unit for applying a separating force to the boundary between the first substrate and the second substrate constituting the composite substrate supported to the supporting surface of the support base and the side surface supporting rollers, thereby separating the composite substrate into the first substrate and the second substrate.