A bookbinding apparatus includes an application roller that applies glue onto a back edge face of a sheet bundle and a bookbinding control unit that positions the application roller onto the back edge face and causes the roller to execute glue application. The bookbinding apparatus applies a required amount of glue determined by a sheet bundle thickness by, after applying side glues to both side surfaces of the sheet bundle, bringing the application roller in contact with a first position within a central region on the back edge face and rotating the roller in a forward direction, bringing the application roller in contact with a second position between the first position and a right side of the sheet bundle, and rotating the roller in the forward direction. The glue is leveled to form a flat layer of adhesive with an adequate thickness.