Patent ID: 7744073

Claim:
A sheet finisher comprising: a saddle stitch unit configured to stitch a center of a sheet bundle in which printed sheets are bundled; a fold unit configured to fold the center stitched by the saddle stitch unit and to form a fold line; and a fold reinforcing unit configured to reinforce the fold line formed by the fold unit, wherein the fold reinforcing unit comprises: a placement table on which the sheet bundle transported from the fold unit is placed; and a roller unit that includes a reinforce roller and moves the reinforce roller along a direction of the fold line while pressing it to the fold line, and wherein the placement table is provided with a groove-like edge clearance along an edge of the sheet bundle, the groove-like edge clearance is formed in a direction perpendicular to the direction of the fold line, and the edge of the sheet bundle descends by the reinforce roller by an effect of a recess shape of the groove-like edge clearance.