An image forming apparatus includes a memory, an image forming device, an authentication device, and a control device. The authentication device performs user authentication. The control device determines whether the stored job requires user authentication. The control device permits the image forming unit to form an image based on the stored job when the job requires user authentication and the authentication device successfully performs user authentication for the job. The control device permits the image forming unit to form an image based on the stored job without user authentication when the job does not require user authentication. The control device selectively supplies power to the authentication device based on whether the stored job requires user authentication.