An image forming apparatus includes a signature verification unit, an execution propriety determination unit, an image forming unit, and a control unit. The signature verification unit decrypts encrypted data with a preset public key in accordance with acquisition of the encrypted data, and uses the decrypted data to verify a digital signature representing authenticity and integrity of a program contained in the decrypted data; the execution propriety determination unit permits execution of a program registered in a preset permission list and the program in which digital signature is verified; the image forming unit forms an image on an image forming medium; and the control unit controls the image forming unit by executing the program permitted to be executed.