A control device for a machine tool including a feed axis driving motor; a first power consumption calculating portion calculating power consumption of the feed axis driving motor; a second power consumption calculating portion calculating power consumption of equipment adapted to be operated by constant power; and a motor control portion determining a target time constant correlated with at least one of acceleration time and deceleration time of the feed axis driving motor, based on a summation of the power consumption calculated by the first power consumption calculating portion and the power consumption calculated by the second power consumption calculating portion, and controlling the feed axis driving motor based on the target time constant.