An image forming apparatus includes an image forming portion, an image reading portion, an analysis processing portion, a generation processing portion, and a printing processing portion. The image forming portion forms an image on a paper sheet. The image reading portion reads a first image from a printed side of a used paper sheet supplied from a sheet feed portion. The analysis processing portion analyzes content of the first image read by the image reading portion. The generation processing portion generates, based on the content of the first image analyzed by the analysis processing portion, a second image that degrades visibility of the first image when the second image is superimposed on the first image. The printing processing portion causes the image forming portion to execute a printing process such that the second image generated by the generation processing portion is superimposed on the first image on the printed side.