The present invention relates to a sheet post-processing device, sheet post-processing system for connecting the sheet post-processing device, and an image forming system installed with the sheet post-processing system. A conveying roller conveys a sheet recording medium on which an image is formed from the image forming device. The sheet post-processing device comprises a a punch unit and a staple unit applying post processing to the sheet recording medium conveyed by the conveying roller. The sheet post-processing device is provided with communication modules(6a2a, 6a2b, 6b2a, 6b2b, 6c2a, 6c2b, 6c2c, 6d2a, 6e2a)serving as communication medium and configured to communicate with linked and connected sheet post-processing devices, and is provided with control modules(6a1, 6b1, 6c1, 6d1, 6e1)serving as control medium and configured to control, via the communication modules, communication for each sheet post-processing device at an arbitrary timing. The sheet post-processing device can operate stably at high speed even when a plurality of sheet post-processing devices are interconnected, and the cost of which is inexpensive. |