A display apparatus which is connectable to a machine tool having a plurality of movable structures (4, 5, 7 to 14), a driving mechanism for driving the movable structures (4, 5, 7 to 14), a numerical controller for controlling operation of the driving mechanism, and an input device for inputting an operation signal to the numerical controller, and which is arranged to display at least an image relating to the movable structures (4, 5, 7 to 14), comprising: a display on which the image is displayed; a display image data storage unit for storing therein data on the image for displaying the image on the display; and a display control unit which is arranged to receive a signal relating to a position of each of the movable structures (4, 5, 7 to 14) from the numerical controller and to read out image data relating to the received movable structures (4, 5, 7 to 14) from the display image data storage unit, to generate a display image in which images of the movable structures (4, 5, 7 to 14) are arranged to have a received positional relationship, and to display the generated display image on the display, characterized in that the display control unit is further configured to, when a selection signal for selecting a movable structure (4, 5, 7 to 14) to be manually operated is input to the numerical controller from the input device, receive the selection signal and generate the display image with a highlighted image of the movable structure (4, 5, 7 to 14) corresponding to the received selection signal, and display the generated display image on the display, and the display control unit is further configured to generate the display image to which an image relating to an axis of movement of the movable structure (4, 5, 7 to 14) corresponding to the selection signal input from the input device is added, and display the generated display image on the display. a display on which the image is displayed; a display image data storage unit for storing therein data on the image for displaying the image on the display; and a display control unit which is arranged to receive a signal relating to a position of each of the movable structures (4, 5, 7 to 14) from the numerical controller and to read out image data relating to the received movable structures (4, 5, 7 to 14) from the display image data storage unit, to generate a display image in which images of the movable structures (4, 5, 7 to 14) are arranged to have a received positional relationship, and to display the generated display image on the display, characterized in that the display control unit is further configured to, when a selection signal for selecting a movable structure (4, 5, 7 to 14) to be manually operated is input to the numerical controller from the input device, receive the selection signal and generate the display image with a highlighted image of the movable structure (4, 5, 7 to 14) corresponding to the received selection signal, and display the generated display image on the display, and the display control unit is further configured to generate the display image to which an image relating to an axis of movement of the movable structure (4, 5, 7 to 14) corresponding to the selection signal input from the input device is added, and display the generated display image on the display.