An apparatus and method of compensating for defective nozzles. Accordingly, in an image forming apparatus having inkjet nozzles (i.e., an inkjet printer), image quality deterioration due to defective nozzles (i.e., nozzles that cannot discharge ink) may be compensated for by replacing data after moving a printer head to an optimum position. Image quality deterioration due to defective nozzles may also be compensated by replacing data to be printed after moving at he printer head to the optimum position.