While a numerical controller is operating, an abnormality of a numerical control section is detected. In response to an abnormality detection signal, a motor deceleration stop control circuit of a servo section is actuated to perform speed control with a speed command “0”, thereby stopping a motor. If an actual speed of the motor becomes not higher than a preset speed, an off command signal for turning off a DO signal is delivered to a PMC section. In response to this off command signal, the PMC section turns off a brake control DO or all DO signals. Thus, a brake device that is attached to the motor is activated to brake the motor.