Hemming dies can be mounted on the respective two clamping jigs (22) of hemming processing stages (S1, S2) each having a turn table as a main part. After the hemming dies are allocated to sub-stages (S11), roller hemming processing is performed by hemming processing robots (1A, 1B) or hemming processing robots (2A, 26). Die storage devices (15A, 15B) for housing a plurality of hemming dies in a line are provided near the hemming processing stages (S1, S2). Hemming dies are changed between the die storage devices (15A, 15B) and the sub-stages (S12) of the hemming processing stages (S1, S2) by first and second die changing robots (17, 19). This makes it possible to provide a roller hemming processing system suitable for roller hemming processing in high-variety low-volume manufacturing.