A sheet finisher of the invention includes a saddle stitch unit configured to stitch a center of a sheet bundle, in which printed sheets are bundled, with a staple, 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, the fold reinforcing unit includes a roller unit that includes a reinforce roller and moves along a direction of the fold line while applying pressure by the reinforce roller to the fold line of the sheet bundle transported from the fold unit, a drive unit configured to move the roller unit along the direction of the fold line, and a control unit configured to control a movement speed of the roller unit, and the control unit causes the roller unit to move at a first speed in an outside of a specified range including the edge of the staple, and causes the roller unit to move at a second speed not higher than the first speed in the specified range including the edge of the staple.