Digital servo control unit and laser processing device

There is provided a digital servo controller unit available, which is used, a D / A converter or converter that suppresses a peak-like pulsation, which is superimposed on a current error signal within a current control circuit, and which has a control function that precipitates is not less than that of units according to the state even if a low-voltage and low-price power supply circuit and power supply is used the art. The digital servo control unit has a low pass first order filter, which acts on an analog signal which is outputted by the D / A-converter and to compensate for a device for stabilizing compensation for a phase delay caused by the low pass filter of first order. An output signal of the first-order low-pass filter is input to a current control circuit as a current command signal. The first-order low-pass filter is formed as a low pass filter having a cutoff frequency that is lower than the sampling frequency. The first-order low-pass filter may be replaced by a notch filter having a cutoff frequency that is equal to a sampling frequency which is equal to or an integer multiple of the Nyquist frequency.