An image forming apparatus is disclosed, the image forming apparatus including a storing unit that stores a program in accordance with which the image forming apparatus operates, an acquiring unit that acquires an update program from an external source, and an updating unit. Before updating the program stored in the storing unit, the updating unit determines whether the update program acquired by the acquiring unit is authentic by checking the electronic signature of the update unit. If the updating unit determines that the update program acquired by the acquiring unit is authentic, the updating unit updates the program stored in the storing unit. Accordingly, the image forming apparatus can improve the reliability of the update program.