Bookbinding apparatus and image forming system

A bookbinding apparatus for producing a booklet by coating an adhesive onto a back side of a bundle of sheets and by pasting a book cover onto the back side of the bundle of sheets, comprising:

• an oblique cutout portion forming section including a first sheet conveying section to convey a sheet one sheet by one sheet, a cutting section that forms a vertically-punched cutout with a predetermined size on an edge of each sheet of the bundle of sheets sequentially one sheet by one sheet conveyed from the first sheet conveying section in such a way that the vertically-punched cutout on a succeeding sheet is formed at a position shifted by a distance smaller than the predetermined size from a position of the vertically-punched cutout on a preceding sheet so that a part of a periphery of the vertically-punched cutout of the succeeding sheet corresponding to the distance is not covered by the preceding sheet so as to form a surface to be coated with an adhesive and an oblique cutout portion is formed along a width of the back side of the bundle of sheets, and a second sheet conveying section to convey each sheet provided with the vertically-punched cutout one sheet by one sheet;
• a sheet bundle accommodating section to receive each sheet provided with the vertically-punched cutout one sheet by one sheet from the second sheet conveying section, to stack the sheet provided with the vertically-punched cutout one sheet by one sheet so as to form the bundle of sheets, and to accommodate the bundle of sheets on the back side of which the oblique cutout portion is formed;
• a coating section that coats the adhesive on the back side of the bundle of sheets;
• and
• a bookbinding section that pastes the book cover on the adhesive-coated back side of the bundle of sheets so as to produce the booklet.