An image output system includes a section that stores registration information in which feature information of a registered user and a target file registered by the registered user are associated with each other, a section that acquires feature information of a current user requesting an output of an image of the target file, a section that obtains an authentication result indicating whether or not two pieces of feature information satisfy a predetermined coincidence condition, by comparing the feature information of the current user to the feature information of the registered user, and a section that controls the output of the image of the target file in accordance with the authentication result.