The present invention provides a motor control device capable of operating a robot properly without stopping a motor that operates the robot even when an instantaneous voltage drop occurs. The motor control device 10 that controls the robot operating motor 102 is equipped with the subtraction unit 109 that calculates the position deviation for which the actual rotational position is subtracted from the position command, the position control unit 110 that converts the position deviation to the speed command, the subtraction unit 111 that calculates the speed deviation for which the actual rotational speed measurement is subtracted from the speed command, the speed control unit 112 that converts the speed deviation to a torque command, the limiter 113 that sets the maximum level of the torque command, the driver 114 that drives the motor 102, and the voltage fluctuation detection unit 115 that detects the voltage fluctuation of the power source 103; in the motor control device 101, when an instantaneous voltage drop is detected by the voltage fluctuation detection unit 115, the position command output unit 108 varies the position command so as to reduce the rotational speed of the motor 102, and the position control unit 110 limits the speed command to be output.