A machine tool control device according to the present invention includes a feedback counter for obtaining A- and B-phase signals of rectangular waves or sine waves and a one-rotation signal, which are outputted from a sensor for detecting the position or speed of a driven axis or a motor, to calculate a feedback count value that is a count value of the number of feedback pulses generated from the A- and B-phase signals; a feedback count value storage unit for storing an inter-one-rotation-signal feedback count value that is the feedback count value counted between the two sequential one-rotation signals; a reference value storage unit for storing an anomaly determination reference value corresponding to the inter-one-rotation-signal feedback count value; and an anomaly cause determination unit for determining the cause of an anomaly by comparison between the inter-one-rotation-signal feedback count value and the anomaly determination reference value.