A display device acquires and displays information on a machine tool that includes a spindle for relatively rotating workpiece and a cutting tool and feed axes for relatively feeding the workpiece and the cutting tool and that performs machining on the workpiece while making the cutting tool and the workpiece swing relatively, and includes: a first information display unit that displays first information indicating a position to which the cutting tool is relatively fed with respect to the workpiece; a second information display unit that displays second information indicating a relationship between the phase of the spindle and the positions of the feed axes; and a range selection unit that selects part of the first information as a selection range, and the second information display unit changes the display range of the second information such that the display range corresponds to the selection range selected by the range selection unit.

A display device acquires and displays information on a machine tool that includes a spindle for relatively rotating workpiece and a cutting tool and feed axes for relatively feeding the workpiece and the cutting tool and that performs machining on the workpiece while making the cutting tool and the workpiece swing relatively, and includes: a first information display unit that displays first information indicating a position to which the cutting tool is relatively fed with respect to the workpiece; a second information display unit that displays second information indicating a relationship between the phase of the spindle and the positions of the feed axes; and a range selection unit that selects part of the first information as a selection range, and the second information display unit changes the display range of the second information such that the display range corresponds to the selection range selected by the range selection unit.