A milling unit of a book binding device removes a coating material adhered to cutting surfaces of coating sheets. A book binding device binding a bunch of sheets fed from a sheet aligning unit includes a sheet aligning plate aligning a section of the bunch of sheets fed from the sheet aligning unit; a gripper fixing the bunch of sheets aligned by the sheet aligning plate; an adhesive unit feeding an adhesive member to the section of the bunch of sheets to bind the bunch of sheets; and a milling unit milling the section of the bunch of sheets before the bunch of sheets is subjected to binding by the adhesive unit.