An image processing apparatus for storing and reading out image data. An authorization code inputting element reads in an authorization code from an authorization medium on which a particular authorization code is recorded and a user identification inputting element inputs user identification information including the individual user authorization number issued at the time of the user being registered. A user control element controls the users by the authorization code and the user identification information, and a function-limiting element limits the scope of functions that can be used by the user in case the user can not be identified by the inputted authorization code or the inputted user identification information. Thus, the storing of image data by an unidentified user can be blocked, and the confidentiality of stored imaged data can be secured.