An electrical discharge machine control device which controls the displacement of the relative positions of a machining electrode and a workpiece so that the relative positions of the electrode and workpiece are changed not only in the main direction in which the workpiece is machined with the electrode but also in a plane perpendicular to the Z-axis without rotating the electrode while a predetermined machining discharge gap is maintained between the electrode and the workpiece. The relative displacement in the perpendicular plane is displayed at an enlarged scale on an X-Y display device which may be a cathode-ray tube with the center of the displacement maintained at a predetermined origin point. An optical encoder detects the movement in the X-Y plane to provide a detection signal. The detection signal is applied through reversible counters to the horizontal and vertical deflection amplifiers of the display device.