To provide a sheet conveying apparatus and an image forming apparatus that can accurately detect a position of a rear end of a sheet regardless of rigidity of the sheet. A rotation axis is positioned to one of a plurality of stop positions by a positioning mechanism, an applied force of a torsion coil spring provided between the rotation axis and a first sensor flag, and an applied force of a torsion coil spring provided between the rotation axis and a second sensor flag are made smaller than an applied force of a pressing spring provided in the positioning mechanism.