Disclosed is a sheet discharging apparatus in which an apparatus main body portion is provided with plural discharging rollers for discharging sheets by rotation, and a shaft coaxially fixed to the discharging rollers. The shaft has an outer diameter smaller than an outer diameter of the discharging roller. At the discharging roller side of the shaft is provided a small-diameter portion, with the outer diameter of the small-diameter portion smaller than the outer diameter of another portion. A projection projects from a portion of the apparatus main body portion, a tip end of the projection being disposed in a step between the small-diameter portion and the other portion of the shaft. Also disclosed is an image forming apparatus having the sheet discharging apparatus, in which an image is formed on a sheet, and the sheet on which the image is formed is discharged by the sheet discharging apparatus.