A display apparatus capable of displaying images of movable structures includes a data storage unit for storing image data and a display control unit which receives signals relating to positions of movable structures from a numerical controller and reads out image data relating to the received movable structures from the storage unit, and generates a display image in which images of the movable structures are arranged to have a positional relationship received and displays the display image on the display. When a selection signal for selecting a movable structure to be operated is input to the numerical controller from an input device, the display control unit receives the selection signal and generates a display image in which the image of the movable structure corresponding to the received selection signal is highlighted and displays the display image on the display.