An image processing apparatus includes a storing unit configured to store comparison data; an analysis unit configured to analyze a print job sent by a requesting user from an information processing apparatus to obtain user information of the requesting user; a comparison unit configured to compare the obtained user information with the comparison data to determine whether registered user information corresponding to the obtained user information is present in the comparison data; and a registration unit configured to register the obtained user information as the comparison data of an authorized user if the registered user information corresponding to the obtained user information is not present in the comparison data. The comparison unit is configured to control execution of a printing process and/or an error process if the registered user information corresponding to the obtained user information is present in the comparison data.