An image forming apparatus includes a character distinguishing unit, a character string extraction unit, a character specifying unit, a determination unit, an overwrite image data generation unit, and a control unit. The overwrite image data generation unit generates, if it is determined by the determination unit that there is a plurality of matches, overwrite image data that has been overwritten such that a character specified by the character specifying unit is indistinguishable as a character. The control unit performs control using the overwrite image data generated by the overwrite image data generation unit so as to cause a printing unit to perform printing on a printed material set in a printed material setting unit.