Image forming apparatus, information processing apparatus, information processing system, authentication method and computer-readable storage medium

An image forming apparatus includes an input part to input authentication information for authenticating a predetermined operation with respect to a registered printing job, an input part to input log-in authentication information for authenticating the predetermined operation from an operation part, an image forming part to form an image of the printing job, and a control part to request input of the authentication information for authenticating the predetermined operation with respect to a printing job that is being executed by the image forming part when the predetermined operation is made from the operation part in a logged in state, and authenticating the predetermined operation with respect to the printing job when authentication of the authentication information input by the input part is successful.