A function control device and method thereof using a remote controller having a minimum number of buttons. The equipment that uses the remote control to control the functions of the image processing equipment includes: a remote control signal receiver, which receives the remote control signal output by the remote control; a storage unit, which stores the main and additional function information of the image processing equipment; a controller, which displays additional function information when the remote control signal contains When a request is made, control the display of the additional function information stored in the storage unit, and control the execution of the function selected based on the displayed additional function information; the display unit displays the additional function information under the control of the controller. Additional function information is displayed in the form of on-screen display data. Therefore, the number of buttons on the remote controller can be minimized. Even if system functions are updated or new functions are added to the system, it is not necessary to upgrade the remote controller to include new function buttons, but to use the original remote controller to control the system operation. Also, the time it takes for the user to learn to use the remote controller can be minimized.