In a bookbinding apparatus provided with a coating device having a coating roller to coat an adhesive onto a spine of a sheet bundle by moving relatively the coating roller and the spine in both forward and backward movement while making the coating roller and the sheet bundle to face each other, the coating device includes: a first regulating member provided downstream of the coating roller in the forward movement, which regulates a thickness of a layer of the adhesive coated on the spine of the sheet bundle; and a second regulating member provided downstream of the coating roller in the backward movement, which regulates a thickness of a layer of the adhesive coated on the spine of the sheet bundle.