There are provided a sheet processing apparatus and an image forming apparatus which can adjust adhesive strength by a simple configuration.A toner image for adhesive strength adjustment is formed on a toner image of a sheet to be bonded by an image forming portion provided in a copying machine body. An adhesive is applied onto a bonding portion of the sheet by a gluing device provided in a finisher. The bonding portion of the sheet onto which the adhesive is applied and the toner image having the toner image for adhesive strength adjustment of the sheet are bonded together by a second pushing-out member and a pair of second folding rollers provided in the finisher. The amount of toner forming the toner image for adhesive strength adjustment formed by the image forming portion is adjusted to adjust the adhesive strength of the adhesive.