An image processing device is provide with an external storage which is detachably connectable to the image processing device, an inputting unit configured to allow a user to input user information, a registration unit configured to register ID information intrinsic to the external storage and the user information input through the inputting unit with registration data in a related manner, a permission unit configured to retrieve the ID information from the external storage and permit access to the external storage connected to the image processing device only if the retrieved ID information is included in the registered ID information which is registered with the registration data, and a data processing unit configured to read/write data from/to the external storage if access to the external storage is permitted by the permission unit.