To bundle a first sealed five bundles on a second sealed five bundles with uniform thickness.

A sheet processing system includes a banding machine (60) which uses a large band (K2) to bundle first collected bundles fed out by a bundle collecting device (11) and then feeds out the bundled first collected bundles as a first bunch of sealed five bundles (S1), the banding machine (60) then using the large band (K2) to bundle again second collected bundles fed out by the bundle collecting device (11) and then feeding out the bundled second collected bundles as a second bunch of sealed five bundles (S2), and a bundle handling device (2) which lays the first and second bunches of sealed five bundles (S1, S2) fed out by the banding machine (60) on top of each other so that small bands (K1) around the first and second bunches (S1, S2) are staggered, the bundle handling device (2) then feeding out the first and second bunches (S1, S2) laid on top of each other.