In a converter unit system, converter units are connected in parallel. The converter unit includes a converter circuit connected to an AC power supply and a DC bus, a first inrush-current suppression resistor connected to the DC bus, a first contactor connected in parallel to the first inrush-current suppression resistor, a smoothing capacitor provided after the first inrush-current suppression resistor and the first contactor, a second contactor externally outputting ON/OFF signal, a voltage detection unit measuring a DC voltage value across the smoothing capacitor, and a control unit controlling the first contactor and the second contactor. The converter unit system includes a third contactor connected to the converter units, and a second inrush-current suppression resistor connected in parallel to the third contactor. When contacts of the second contactors are all closed, a contact of the third contactor is closed.