A bookbinding system having: at least one paper feeding tray (21, 23) suitable for storing paper sheets (P1, P2); a paper sheet bundle production unit suitable for using the paper sheets supplied from the paper feeding tray as text paper sheets to produce a paper sheet bundle composed of the plural text paper sheets; a shaping unit suitable for using the paper sheet supplied from the paper feeding tray as a cover paper sheet, suitable for contacting a spine (P2R) of the paper sheet bundle and the cover paper sheet with each other, and suitable for shaping a booklet by binding the paper sheet bundle using the cover paper sheet by case binding; and the bookbinding system comprising a control unit (17, 50) suitable for selecting the paper feeding tray storing paper sheets having a size fitting within a region configured with a front surface, a back surface, and the spine (PSa) of the paper sheet bundle, suitable for allowing the shaping unit to shape the booklet using the paper sheet stored in the paper feeding tray as the cover paper sheet; wherein the control unit (17, 50) is suitable for selecting the paper feeding tray (21, 23) storing paper sheets whose length (Lp) in the longitudinal or lateral direction matches the length in the direction orthogonal to the thickness direction at the spine of the paper sheet bundle (PSa) when allowing the shaping unit to shape the booklet; characterised in that the control unit (17, 50) is suitable for controlling the shaping unit to adjust the relative arrangement of the paper sheet bundle and the cover paper sheet, so that the area of a region covered with the cover paper sheet on the front surface of the paper sheet bundle is larger than the area of a region covered with the cover paper sheet on the back surface of the paper sheet bundle. at least one paper feeding tray (21, 23) suitable for storing paper sheets (P1, P2); a paper sheet bundle production unit suitable for using the paper sheets supplied from the paper feeding tray as text paper sheets to produce a paper sheet bundle composed of the plural text paper sheets; a shaping unit suitable for using the paper sheet supplied from the paper feeding tray as a cover paper sheet, suitable for contacting a spine (P2R) of the paper sheet bundle and the cover paper sheet with each other, and suitable for shaping a booklet by binding the paper sheet bundle using the cover paper sheet by case binding; and the bookbinding system comprising a control unit (17, 50) suitable for selecting the paper feeding tray storing paper sheets having a size fitting within a region configured with a front surface, a back surface, and the spine (PSa) of the paper sheet bundle, suitable for allowing the shaping unit to shape the booklet using the paper sheet stored in the paper feeding tray as the cover paper sheet; wherein the control unit (17, 50) is suitable for selecting the paper feeding tray (21, 23) storing paper sheets whose length (Lp) in the longitudinal or lateral direction matches the length in the direction orthogonal to the thickness direction at the spine of the paper sheet bundle (PSa) when allowing the shaping unit to shape the booklet; characterised in that the control unit (17, 50) is suitable for controlling the shaping unit to adjust the relative arrangement of the paper sheet bundle and the cover paper sheet, so that the area of a region covered with the cover paper sheet on the front surface of the paper sheet bundle is larger than the area of a region covered with the cover paper sheet on the back surface of the paper sheet bundle.