In a sheet finisher including an adhesive coating section, a movement mechanism, a control section that controls actions of the adhesive coating section and of the movement mechanism, is capable of multiple coating on a spine of a sheet bundle by causing the movement mechanism to move the adhesive coating section reciprocally and relatively with respect to the spine, and is capable of conducting a preparation process to cause the rotary adhesive supplying section to rotate for a prescribed period of time in a rotation direction corresponding to a movement direction of the adhesive coating section under a condition of no coating of the adhesive on the spine of the sheet bundle, after the movement direction of the adhesive coating section and the rotation direction of the rotary adhesive supplying section are switched, following the reciprocating movement in the case of the multiple coating.