To shorten a capacitor charging time while avoiding erroneous ignition caused by the distortion of a power supply voltage and keeping a rush current unchanged.

A capacitor charging control method for a thyristor converter device comprises: a thyristor that rectifies an AC voltage; a CPU that outputs an on/off signal to a thyristor driver for driving the thyristor; a voltage detection sensor that measures the AC voltage and a capacitor charging voltage; and a capacitor connected to a DC circuit. The AC voltage and the capacitor charging voltage are measured by the voltage detection sensor, whereby a differential voltage between a thyristor ignition phase voltage and the capacitor charging voltage is obtained, and only when the thyristor ignition phase voltage is lowered to a specified voltage or lower that is obtained from the differential voltage, the thyristor is ignited.