A joining roller rolls on the surface of a reinforcing substrate held by a center and side latch claws so as to be close and opposite to an wafer placed and held on a holding table in the condition that an adhesive sheet is adhered on the surface, whereby joining proceeds. As the joining roller rolls, both of the latch claws oscillate downward and the latch claws themselves move down while keeping the bend of the reinforcing substrate nearly constant, and retract when the joining roller approaches the latch claws.