In a multi-function input/output device, an optical reading unit optically reads an optically readable code from a device control setting medium on which device control setting information, including use authentication information and unit-control-setting information for a document input control setting unit, a document-data-processing control setting unit, and a document-data-output control setting unit, is recorded. The device control setting information including the use authentication information is recognized from the code read by the optical reading unit. A user authentication unit authenticates the user by using a use authentication code of the use authentication information. A setting processing unit sets the unit-control-setting information based on a recognition result of the device control setting information and the use authentication information.