A bookbinding apparatus for forming a booklet by coating an adhesive on a spine of a stack of sheets, including: a coating apparatus, which has an adhesive reservoir to store a liquid of the adhesive, and a coating roller to coat on the spine the adhesive scooped up from the adhesive reservoir; a pellet storage section to store pellets of the adhesive; a replenishing section to replenish the pellets of the adhesive into the adhesive reservoir; an adhesive quantity sensor to detect a liquid level in the adhesive reservoir; and a controller to control the replenishing section based on a detection signal of the adhesive quantity sensor, wherein the controller controls a rate of replenishing amount of the pellets by controlling the replenishing section based on information of the stack of sheets.