An operating device for a CNC machine includes an operating portion, an encoder, a memory unit, a microprocessor, a display unit, and a controller. The operating portion includes a rotary button and a confirm button. The encoder is connected to the rotary button and the confirm button for generating corresponding position codes. The memory unit stores a number of function menus corresponding to a number of operating instructions. The microprocessor is connected between the encoder and the memory unit for receiving the position codes from the encoder and invoking the corresponding function menus from the memory unit. The display unit is connected to the microprocessor for displaying the function menus. The controller is connected to the microprocessor for executing input instructions.