An image forming apparatus comprising: an operation display unit that includes an operation display section having function setting keys for receiving various function setting instructions, a storage unit in which default setting information that defines function setting keys to be displayed on the operation display section is stored; a connecting unit configured to connect a portable storage medium that can store user-specific setting information customized to individual users that defines function setting keys to be displayed on the operation display section; and a control unit configured, when the portable storage medium in which user-specific setting information is stored is connected to the connecting unit, to perform a process based on the user-specific setting information stored in the portable storage medium without changing the default setting information stored in the storage unit; characterized in that, wherein when the portable storage medium in which the user-specific setting information is stored is connected to the connecting unit, the control unit causes the operation display section to display the function setting keys based on the user specific setting information stored in the portable storage medium without changing the default setting information stored in the storage unit, the operation display section is adapted to receives one of an instruction to operate the image forming apparatus on the basis of the default setting information stored in the storage unit and an instruction to operate the image forming apparatus on the basis of the user-specific setting information stored in the portable storage medium. an operation display unit that includes an operation display section having function setting keys for receiving various function setting instructions, a storage unit in which default setting information that defines function setting keys to be displayed on the operation display section is stored; a connecting unit configured to connect a portable storage medium that can store user-specific setting information customized to individual users that defines function setting keys to be displayed on the operation display section; and a control unit configured, when the portable storage medium in which user-specific setting information is stored is connected to the connecting unit, to perform a process based on the user-specific setting information stored in the portable storage medium without changing the default setting information stored in the storage unit; characterized in that, wherein when the portable storage medium in which the user-specific setting information is stored is connected to the connecting unit, the control unit causes the operation display section to display the function setting keys based on the user specific setting information stored in the portable storage medium without changing the default setting information stored in the storage unit, the operation display section is adapted to receives one of an instruction to operate the image forming apparatus on the basis of the default setting information stored in the storage unit and an instruction to operate the image forming apparatus on the basis of the user-specific setting information stored in the portable storage medium.