A thyristor starting device includes: a converter which converts AC power supplied from an AC power source into DC power; a DC reactor which smooths a DC current; an inverter which converts the DC power provided from the converter into AC power, and supplies the AC power to a synchronous machine; a gate pulse generation circuit which generates a gate pulse to be provided to thyristors of the converter and the inverter; a control unit which sets a phase control angle of the gate pulse to be provided to the thyristors of the converter, by controlling a current of the converter such that the DC current flowing into the DC reactor matches a current command value; and an abnormality detection unit which compares a detection value of the DC current with the current command value, and determines an abnormality in the gate pulse based on a comparison result.